Windows partition refusing to boot after cloning and extending

I recently bought a new, bigger and faster ssd. I needed to clone the disk and extend the windows partition, and did this with Acronis True Image, whose cloning function also happens to extend the partition automatically in just a couple of clicks. All went well, I booted from the new ssd a couple of times. Things looked right, so I decided to format my old ssd. Next reboot, the spinning dots that appear at boot stop moving after a second maybe, then I get the 0xc0000001 error with no other information except that I should use recovery media to repair.

So this is what I tried:

1. Automatic repair
2. chkdsk
3. bootrec /fixboot and rebuildbcd which in turn resulted in "access denied" and no installations found
4. mounting and formatting the efi partition, then copying data from c:\windows\boot... following various tutorials on different sites which all reported the same thing
5. Erasing the efi and msr partition and then rebuilding them, like this
6. Doing a fresh install then swapping the windows partition with the old one, so that efi, msr, and restore are all good and new and without errors
7. Macrium Reflect windows boot fix function in the rescue media, which recognized my installation and windows version

All these always result in the same error. At this point, it can't be a problem with the efi partition like most sources seem to report. I really can't do a fresh install, it's an audio studio workstation with Steinberg Cubase installed, and hundreds of plugins and settings which I couldn't possibly recover.

Apart from your very welcome suggestions, opinions and things to try, what bothers me the most is that I can't get any clue to where the procedure is stopping, which file could be corrupted or missing... I can't find a way to get a verbose mode or a log... just the spinning dots.

All I have now is an acronis true image tib of the partition which I restored multiple times and the files SEEM to be all there and uncorrupted...