Having trouble stopping U-Boot autoboot

Background:

I have an old Seagate BlackArmor NAS 110 that I'm trying to install Debian on by following the instructions here: https://github.com/hn/seagate-blackarmor-nas.

I have a couple of USB to TTL serial adapters (one FTDI chipset and the other Prolific) that I've tried and have run into the same issue with both. I have made the connection to the serial port on the board of the NAS using a multimeter to make sure I've gotten the pinout correct.

Problem:

I'm not able to stop the autoboot process by pressing keys and any point during the boot process. The device also does not seem to respond to any keystrokes although they are echoed back.

What I've Tried So Far:

• Using USB to TTL serial adapters with two different chipsets
• Using the adapters on two different computers (MacBook Pro and a ThinkPad)
• Using different operating systems (MacOS, Windows 10, Ubuntu 20.04)
• Using different terminal programs (Screen, Minicom, Putty)
• Turned off hardware and software flow control
• Tested output of adapters by shorting RX and TX pins and seeing keystrokes echoed back
• Commands seem to be sent to device as when I type I see my commands echoed back (not sure if this is supposed to happen)

I've been at this for a few days and can't figure it out. I've also recorded my screen while experiencing the issue: https://streamable.com/xl43br. Can anyone see where I'm going wrong?

Terminal output while experiencing the problem:

Welcome to minicom 2.7.1

OPTIONS: 
Compiled on Nov 15 2020, 08:12:42.
Port /dev/tty.usbserial-AQ00KV6T, 16:51:31

Press Meta-Z for help on special keys

???
         __  __                      _ _
        |  \/  | __ _ _ ____   _____| | |
        | |\/| |/ _` | '__\ \ / / _ \ | |
        | |  | | (_| | |   \ V /  __/ | |
        |_|  |_|\__,_|_|    \_/ \___|_|_|
 _   _     ____              _
| | | |   | __ )  ___   ___ | |_ 
| | | |___|  _ \ / _ \ / _ \| __| 
| |_| |___| |_) | (_) | (_) | |_ 
 \___/    |____/ \___/ \___/ \__|  ** uboot_ver:v0.0.5 **

 ** MARVELL BOARD: MONO LE 

U-Boot 1.1.4 (Nov  6 2009 - 11:15:26) Marvell version: 3.4.18

U-Boot code: 00600000 -> 0067FFF0  BSS: -> 006CDE60

Soc: 88F6192 A1 (DDR2)
CPU running @ 800Mhz L2 running @ 400Mhz
SysClock = 200Mhz , TClock = 166Mhz 

DRAM CAS Latency = 3 tRP = 3 tRAS = 8 tRCD=3
DRAM CS[0] base 0x00000000   size 128MB 
DRAM Total size 128MB  16bit width
Addresses 8M - 0M are saved for the U-Boot usage.
Mem malloc Initialization (8M - 7M): Done
NAND:d32 MB

Marvell Serial ATA Adapter
Integrated Sata device found


CPU : Marvell Feroceon (Rev 1)
Scanning partition header:
Found sign PrEr at c0000
Found sign KrNl at 2c0000
Found sign RoOt at 540000

Streaming disabled 
Write allocate disabled


USB 0: host mode
PEX 0: interface detected no Link.
Net:   egiga0 [PRIME]
 0  any key to stop autoboot:  1 

NAND read: device 0 offset 0xc4000, size 0x195200

Reading data from 0x259000 -- 100% complete.
 1659392 bytes read: OK
Calculate CRC32:
crc32 checksum Pass

NAND read: device 0 offset 0x2c4000, size 0x21c000

Reading data from 0x4dfe00 -- 100% complete.
 2211840 bytes read: OK
Calculate CRC32:
crc32 checksum Pass
## Booting image at 00040000 ...
   Image Name:   Linux-2.6.22.18
   Created:      2009-11-06   3:38:29 UTC
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    2211388 Bytes =  2.1 MB
   Load Address: 00008000
   Entry Point:  00008000
   Verifying Checksum ... OK
OK

Starting kernel ...

Uncompressing Linux.......................................................................................................................................... done, booting the kernel.
Linux version 2.6.22.18 (root@jasonDev.localdomain) (gcc version 4.2.1) #1 Fri Nov 6 11:38:22 CST 2009 v0.0.7
CPU: ARM926EJ-S [56251311] revision 1 (ARMv5TE), cr=00053977
Machine: Feroceon-KW
Using UBoot passing parameters structure
Memory policy: ECC disabled, Data cache writeback
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 4, 32 byte lines, 128 sets
CPU0: D cache: 16384 bytes, associativity 4, 32 byte lines, 128 sets
Built 1 zonelists.  Total pages: 32512
Kernel command line: console=ttyS0,115200 mtdparts=nand_mtd:0x000a0000@0x0(uboot),0x00010000@0x000a0000(param),0x00200000@0x000c0000(preroot),0x00280000@0x002c0000(uimage),0x01a000000
PID hash table entries: 512 (order: 9, 2048 bytes)
Console: colour dummy device 80x30
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Memory: 128MB 0MB 0MB 0MB = 128MB total
Memory: 109056KB available (4048K code, 289K data, 128K init)
Security Framework v1.0.0 initialized
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
NET: Registered protocol family 16

CPU Interface
-------------
SDRAM_CS0 ....base 00000000, size 128MB 
SDRAM_CS1 ....disable
SDRAM_CS2 ....disable
SDRAM_CS3 ....disable
PEX0_MEM ....base e8000000, size 128MB 
PEX0_IO ....base f2000000, size   1MB 
INTER_REGS ....base f1000000, size   1MB 
NFLASH_CS ....base fa000000, size   2MB 
SPI_CS ....base f4000000, size  16MB 
BOOT_ROM_CS ....no such
DEV_BOOTCS ....no such
CRYPT_ENG ....base f0000000, size   2MB 

  Marvell Development Board (LSP Version KW_LSP_4.2.7_patch21_with_rx_desc_tuned)-- MONO  Soc: 88F6192 A1 LE

 Detected Tclk 166666667 and SysClk 200000000 
MV Buttons Device Load
Marvell USB EHCI Host controller #0: c05b4600
PEX0 interface detected no Link.
PCI: bus0: Fast back to back transfers enabled
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
NET: Registered protocol family 2
Time: kw_clocksource clocksource has been installed.
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP reno registered
checking if image is initramfs...it isn't (bad gzip magic numbers); looks like an initrd
Freeing initrd memory: 16384K
RTC registered
Use the XOR engines (acceleration) for enhancing the following functions:
  o RAID 5 Xor calculation
  o kernel memcpy
  o kenrel memzero
Number of XOR engines to use: 4
cesadev_init(c00116c4)
mvCesaInit: sessions=640, queue=64, pSram=f0000000
MV Buttons Driver Load
VFS: Disk quotas dquot_6.5.1
Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
Installing knfsd (copyright (C) 1996 okir@monad.swb.de).
JFFS2 version 2.2. (NAND) ?Â?© 2001-2006 Red Hat, Inc.
fuse init (API version 7.8)
SGI XFS with large block numbers, no debug enabled
io scheduler noop registered
io scheduler anticipatory registered (default)
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO 0xf1012000 (irq = 33) is a 16550A
serial8250.0: ttyS1 at MMIO 0xf1012100 (irq = 34) is a 16550A
RAMDISK driver initialized: 2 RAM disks of 16384K size 1024 blocksize
loop: module loaded
Loading Marvell Ethernet Driver:
  o Cached descriptors in DRAM
  o DRAM SW cache-coherency
  o Single RX Queue support - ETH_DEF_RXQ=0
  o Single TX Queue support - ETH_DEF_TXQ=0
  o TCP segmentation offload enabled
  o Receive checksum offload enabled
  o Transmit checksum offload enabled
  o Network Fast Processing (Routing) supported
  o Driver ERROR statistics enabled
  o Driver INFO statistics enabled
  o Proc tool API enabled
  o Rx descripors: q0=256
  o Tx descripors: q0=532
  o Loading network interface(s):
    o egiga0, ifindex = 1, GbE port = 0

Warning: Giga 1 is Powered Off

mvFpRuleDb (c73ab000): 1024 entries, 4096 bytes
e100: Intel(R) PRO/100 Network Driver, 3.5.17-k4-NAPI
e100: Copyright(c) 1999-2006 Intel Corporation
Integrated Sata device found
scsi0 : Marvell SCSI to SATA adapter
scsi1 : Marvell SCSI to SATA adapter
NFTL driver: nftlcore.c $Revision: 1.98 $, nftlmount.c $Revision: 1.41 $
NAND device: Manufacturer ID: 0xec, Chip ID: 0x75 (Samsung NAND 32MiB 3,3V 8-bit)
Scanning device for bad blocks
7 cmdlinepart partitions found on MTD device nand_mtd
Using command line partition definition
Creating 7 MTD partitions on "nand_mtd":
0x00000000-0x000a0000 : "uboot"
0x000a0000-0x000b0000 : "param"
0x000c0000-0x002c0000 : "preroot"
0x002c0000-0x00540000 : "uimage"
0x00540000-0x01f40000 : "rootfs"
0x01f40000-0x02000000 : "misc"
0x00000000-0x02000000 : "flash"
ehci_marvell ehci_marvell.70059: Marvell Orion EHCI
ehci_marvell ehci_marvell.70059: new USB bus registered, assigned bus number 1
ehci_marvell ehci_marvell.70059: irq 19, io base 0xf1050100
ehci_marvell ehci_marvell.70059: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 1 port detected
USB Universal Host Controller Interface driver v3.0
usb 1-1: new high speed USB device using ehci_marvell and address 2
usb 1-1: configuration #1 chosen from 1 choice
hub 1-1:1.0: USB hub found
hub 1-1:1.0: 4 ports detected
usbcore: registered new interface driver usblp
drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver
Initializing USB Mass Storage driver...
usbcore: registered new interface driver usb-storage
USB Mass Storage support registered.
mice: PS/2 mouse device common for all mice
i2c /dev entries driver
attach_adapter....
md: linear personality registered for level -1
md: raid0 personality registered for level 0
md: raid1 personality registered for level 1
md: raid10 personality registered for level 10
raid6: int32x1     73 MB/s
raid6: int32x2     80 MB/s
raid6: int32x4     83 MB/s
raid6: int32x8     74 MB/s
raid6: using algorithm int32x4 (83 MB/s)
md: raid6 personality registered for level 6
md: raid5 personality registered for level 5
md: raid4 personality registered for level 4
raid5: measuring checksumming speed
   arm4regs  :   722.800 MB/sec
   8regs     :   503.200 MB/sec
   32regs    :   600.000 MB/sec
raid5: using function: arm4regs (722.800 MB/sec)
device-mapper: ioctl: 4.11.0-ioctl (2006-10-12) initialised: dm-devel@redhat.com
dm_crypt using the OCF package.
usbcore: registered new interface driver hiddev
usbcore: registered new interface driver usbhid
drivers/hid/usbhid/hid-core.c: v2.6:USB HID core driver
wix gpio_init
Advanced Linux Sound Architecture Driver Version 1.0.14 (Thu May 31 09:03:25 2007 UTC).
ALSA device list:
  No soundcards found.
TCP cubic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
RAMDISK: cramfs filesystem found at block 0
RAMDISK: Loading 1620KiB [1 disk] into ram disk... done.
VFS: Mounted root (cramfs filesystem) readonly.
Freeing init memory: 128K
Enter Pre-Root FileSystem:
FW_UPDATE_FLAG_RES:1
BOARDTEST_FALG:0
DSK1_RES:1
DSK2_RES:1
DSK3_RES:1
DSK4_RES:1
DSK1_S_RES:
DSK2_S_RES:
DSK3_S_RES:
DSK4_S_RES:
CHK_RES:1
MD0CHK_RES:1
init started:  BusyBox v1.1.1 (2008.10.08-08:58+0000) multi-call binary
Starting pid 396, console /dev/ttyS0: '/etc/init.d/rcS'
Starting network...
Starting inetd... OK
NOT_DEF_RES:0
EXT3-fs: unable to read superblock
FAT: unable to read boot sector
EXT3-fs: unable to read superblock
EXT2-fs: unable to read superblock
FAT: unable to read boot sector
FAT: unable to read boot sector
egiga0: started
admindasdas

So it turns out there is a short somewhere between the RX pin and the +3.3V pin which is not allowing me to send anything to the board. Thank you to those who have commented.