3DS XL Charges but wont turn on

I got a 3DS XL here that does seem to charge (the charging light comes on) but no matter what I do it won’t turn on. If I hit the power button nothing happens, it doesn’t even turn on for a second. Upon opening the device I did find some water damage though it was nothing major and was mainly on the charging components, which it still seems to charge fine. (I did notice some discoloration/darkening on two components) I went ahead and tested all the charging components to make sure everything was fine since there was some water damage and everything tested fine. I took out the daughterboard for the battery and what not and there was a small amount of water damage as well, which I cleaned off and still, this 3DS won’t turn on.

My question is what can I test to find the culprit?

I know there might be an issue with a component on the mainboard or daughterboard, whether it is a capacitor, resistor, fuse whatever and I am willing to replace it. For all, I know it could be the ribbon cable connecting the two boards. But with that said I want to make sure I know what to buy to fix it before I go spend the money to fix it.

Photos of the charging components (main water damaged area) and the daughterboard.