The water detection sticker on the top of the battery certainly isn't white any more which leads me to believe the phone has been exposed to water.

If you can find out how long ago the phone was exposed to water and you find it was not too long ago it may be worth taking apart the phone and cleaning with some form of contact cleaner such as wd40 to draw out the water then try turning in on.

A possible re-flash and battery replacement may also help, although if this doesn't you will probably be left with a water damaged brick.