Water damaged MacBook Pro 13" early 2015 doesn't work without charger

So I got a MacBook Pro 13" that had a glass of water spilled into it. Found some corrosion on the battery circuit board (the one attached to the battery). Cleaned it up. The computer works fine except that it doesn't work without the magsafe charger. There is an orange light on the magsafe power supply and the battery percentage is stuck on 89%, and indicates charging. But as soon as I remove the magsafe charger the computer shuts down immediately. What can be faulty? The battery itself? Or the magsafe DC-in board?

The logic board itself had no corrosion at all. Removed it and checked both sides, it was perfect. There was only corrosion on the battery's circuit board, the one where the battery connector is attached to.

Actually now that I am in OS X it says it isn't charging. Probably bad battery then I guess?

The battery has 89% charge and still the computer shuts down immediately when charger is removed. What would that indicate?

I tried resetting pram and smc. I also tried smc cycle, by holding power button without charger plugged in, for 10 seconds, then connecting charger and holding power button another 10 seconds. Then when I tried turning it on the fans were spinning at 100% and coconut battery didn't report a battery installed. After that I rebooted machine and reset smc again but the problem still persists with 89% charge, like in the image above.