Sorry this happened to you... I hope it can be saved.
The chip itself *might* not be damaged.

What causes damage to electronics when it gets wet is primarily electrolysis of the exposed metal parts (traces and contacts).
To prevent this (for future reference), whenever any electronic device gets wet, pull the power supply (battery) from it as fast as humanly possible and dry it thoroughly before re-applying power.

That said, there's two things that might be happening here.

The first is that one (or more) of the traces may be corroded completely away. This is extremely difficult to fix unless you are amazingly good at soldering (you'd need to be a pro with magnifying equipment).

The second is that some of the corrosion is actually bridging some of the contacts or traces. I'm hoping this is what happened here, and think it might be, since you indicate a higher than normal battery load. Hopefully, it didn't bridge across something that can cause damage to the chip due to application of voltage above spec for that connection to the chip.
If you're *extremely* careful, you can clean up the corrosion from the contacts and you might be able to save the device. I would use a stiff brush, but not a metal one as the metal may be damaging. You might be able to use some rubbing alcohol (stronger the better, like 90%+) with a swab to clean some light stuff too. Just make sure it's 100% dry before re-assembly.

As to how to disassemble it (and re-assemble later)... I can't help you there (sorry). I've only owned mine for a few days.