Watchdog timer rebooting during install - no access to BIOS to change timers

First time posting, as I typically like to figure this stuff out by myself, but need some guidance from the experts.

I have an piece of hardware that runs a specialized version of openWRT, which is locked down and I do not want to use anymore. I want to install a Linux OS on this platform and run a few small containerized apps to play around with.

The problem is that it is a headless machine with only serial port access (USB to UART bridge). I've compiled some USB boot images which redirect the output to console, however - I think - the existing watchdog timer reboots the hardware in the middle of the install. I figure this is a BIOS setting, but I cannot for the life of me figure out how to access the BIOS or at least edit the timer in the linux CLI (I have root access). There is also NOT a dedicated IPMI interface I can use.

I've been trying and trying to figure this out for the past 6 months, but I am stuck. Please help!

Here is the initial boot sequence from the box: Sage_coreboot-4.0-01.00.00.04 Wed Jan 17 10:12:57 PST 2018 starting... Mainboard: Mohon Peak Version 2.0 Build: SageBios_Mohon_Peak - 292 Detected C0 stepping SOC Setting up static southbridge registers... done. done. RTC Init Setting up static northbridge registers... done. Back from rangeley_early_initialization() Starting the Intel FSP (early_init) ConfigureDefaultUpdData PcdEnableIQAT 1 PcdEnableLan 1 PcdEnableLan 1 PcdEnableLan 1 PcdEnableLan 1 PcdEnableUsb20 1 PcdEnableSata2 1 PcdEnableSata3 1 default PMC_CFG reg: 0x8 abase is: 0x400 default TCO_STS reg: 0x0 default TCO_TMR reg: 0x640000 Raising Watchdog timer timeout to 3min...TCO_TMR value applied: 0x640000 done.

Thanks in advance!

Edit: Here is my dmidecode - I don't see any reference to a timer (should be type 23). Now I am totally lost.

# dmidecode 2.12
SMBIOS 2.7 present.
7 structures occupying 396 bytes.
Table at 0x7FBEE020.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
        Vendor: coreboot
        Version: 
        Release Date: 01/17/2018
            ROM Size: 8192 kB
        Characteristics:
                PCI is supported
                PC Card (PCMCIA) is supported
                BIOS is upgradeable
                Selectable boot is supported
                ACPI is supported
                Targeted content distribution is supported
        BIOS Revision: 4.0
        Firmware Revision: 0.0

Handle 0x0001, DMI type 1, 27 bytes
System Information
        Manufacturer: 
        Product Name: 
        Version: 2.8
        Serial Number: 
        UUID: 
        Wake-up Type: Reserved
        SKU Number: None Provided
        Family: None Provided

Handle 0x0002, DMI type 2, 8 bytes
Base Board Information
        Manufacturer: VeloCloud Networks, Inc.
        Product Name: EDGE520
        Version: 2.8
        Serial Number: 1811DF01028

Handle 0x0003, DMI type 3, 21 bytes
Chassis Information
        Manufacturer: 
        Type: Desktop
        Lock: Not Present
        Version: Not Specified
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Boot-up State: Safe
        Power Supply State: Safe
        Thermal State: Safe
        Security Status: None
        OEM Information: 0x00000000
        Height: Unspecified
        Number Of Power Cords: Unspecified
        Contained Elements: 0

Handle 0x0004, DMI type 4, 42 bytes
Processor Information
        Socket Designation: P0
        Type: Central Processor
        Family: Pentium Pro
        Manufacturer: GenuineIntel
        ID: D8 06 04 00 FF FB EB BF
        Signature: Type 0, Family 6, Model 77, Stepping 8
        Flags:
            FPU (Floating-point unit on-chip)
            VME (Virtual mode extension)
            DE (Debugging extension)
            PSE (Page size extension)
            TSC (Time stamp counter)
            MSR (Model specific registers)
            PAE (Physical address extension)
            MCE (Machine check exception)
            CX8 (CMPXCHG8 instruction supported)
            APIC (On-chip APIC hardware supported)
            SEP (Fast system call)
            MTRR (Memory type range registers)
            PGE (Page global enable)
            MCA (Machine check architecture)
            CMOV (Conditional move instruction supported)
            PAT (Page attribute table)
            PSE-36 (36-bit page size extension)
            CLFSH (CLFLUSH instruction supported)
            DS (Debug store)
            ACPI (ACPI supported)
            MMX (MMX technology supported)
            FXSR (FXSAVE and FXSTOR instructions supported)
            SSE (Streaming SIMD extensions)
            SSE2 (Streaming SIMD extensions 2)
            SS (Self-snoop)
            HTT (Multi-threading)
            TM (Thermal monitor supported)
            PBE (Pending break enabled)
    Version:         Intel(R) Atom(TM) CPU  C2358  @ 1.74GHz
    Voltage: Unknown
    External Clock: 200 MHz
    Max Speed: 1600 MHz
    Current Speed: 1600 MHz
    Status: Populated, Enabled
    Upgrade: None
    L1 Cache Handle: Not Provided
    L2 Cache Handle: Not Provided
    L3 Cache Handle: Not Provided
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified
    Core Count: 16
    Characteristics: None

Handle 0x0005, DMI type 32, 11 bytes
System Boot Information
    Status: No errors detected

Handle 0x0006, DMI type 127, 4 bytes
End Of Table