Macbook Pro Water Damage - Now only boots while holding shift key. Crashes as soon as released

Hi,

I have a 2015 Macbook Pro that had a small amount of water spilled on it. Everything seemed fine for a few days. Then it stopped booting properly and crashed after the chime but before the Apple logo. The only way I can make it boot beyond that is holding down the shift key, so in Safe Mode. However, once at the login screen as soon as I release the shift key to enter the password it crashes. I can hold the shift key for minutes without crashing but a few seconds after releasing it crashes every time.

I have taken out all the components and can't see any moisture, corrosion, or signs of damage to the logic board. I have let it dry for 4 days with a fan and heater.

What could be wrong do you think? Would the shift key issue suggest a keyboard replacement might work?

Help greatly appreciated!