How do you fix bluetooth?

wow, this is almost a year old - anyway - there are many people with a similar problem.

the water most likely shortened some parts on the mainboard.

use the gps antenna guide (click) to disassemble the phone (you can stop at the point where the "board" comes out of the rear panel)

use some rubbing alcohol and a soft paintbrush (should have short hair) to clean the "greenish/white" areas (looks a little bit like mold).

be careful not to break anything on the "board" - let it dry and reassemble the phone.

wifi/bt and gps are using the same antenna - so look in the area of connector 6 - but the damages can be all over the "board".

good luck