Slight water damage. Turns on but only when magsafe is connected.

2 ISSUES

I purchased a used mac from QUALITY MACS ( not so quality), when i received it i pressed the power button and didn't turn on. i charged it till the light turn green and pressed power button and nothing happened until the second time. How and what do i need to replace the power button (not key) but w.e. is under the key.

2nd issue

2 months later 5 drops of grape juice entered through the vent slit in bottom rear while OFF. Immediately dried it with a space heater on low. i let it air dry for a whole week.

pressed power button and nothing ( keep in mind it was at 80 percent battery). I connected the magsafe and immediately turned on without pressing power button.

a warning message popped up on battery icon top right. magsafe led stays orange.

As soon as you disconnect magsafe it turns off and therefore only turns/stays on with magsafe connected. I take the battery needs replacing but how do i address the issue with the power button not being responsive.???

p.s. i purchased a extended warranty after 30 day warranty was up. 1 and half year later i looked further into the company providing warranty (CPS) and read really bad review. not trying to risk sending my mac to them and i willing to fix it myself

HELP