So a while back due to a drink spill, I managed to fry a bunch of parts of my XPS 13 (9350), and had to replace many parts including the motherboard. I've had to pull it apart before, so I wasn't too concerned about pulling it open and replacing the fried parts, and after some fiddling I got it to boot up, seemingly fine.

However, the system was unstable, freezing and crashing often (this happened when certain diagnostics were run especially, I think it was an overheating problem due to trying to use the old dry thermal paste on the new board).

For some reason, it decided after one crash to update the BIOS (I had not told it to do so), and predictably it froze halfway through. None of the official advice on how to recover the BIOS has worked for me (i.e. download and correctly rename a bios file from dell, put on a properly formatted USB, put in laptop, hold esc and ctrl while plugging in the power cable). When I press the power button, the screen never even seems to turn on, and the keyboard backlight only briefly flashes before turning off, but the exact behaviour can change between attempts.

Doing the whole "unplug battery and CMOS battery, hold power to release static" thing doesn't help, but I have noticed that when I do that and then try and boot several times, the computer will eventually start producing error code LED flashes, until it just starts flashing amber constantly and quickly.

I would really prefer not having to buy another motherboard. Is there even remotely a chance of fixing this, or do I just have to bite the bullet and get a new motherboard?