I would:
Check the output on the power supply, correct output V / A?
At board, with supply connected, check one side of caps (other connected to ground) for voltage.
To check that a Cap has the correct capacitance, you would need to remove it from the board, and have a meter that can correctly test capacitors. These tantalum caps in the pic are filter caps, if you look around in pic, youll see where power comes in -- and an ic -- so those are all there to knock out noise @60hz. One side will connect to ground, one side to +source.
Cant test most components on board because you would need to know designated operating/in-circuit values. So you would need to remove any bricks to test, caps or resistors. Testing capacitors with a regular meter will always show an open on a capacitor if you check it for resistance -- those bricks only go bad when you heat them up and cook the ends off of them, or they physically crack/break.
You would then need to determine Res, and Cap of each component you remove. With components removed for testing, you can clean up pads on PWB and test for bad solder joints, damaged pads, etc.
As this is listed as water damage, remove PWB:
Clean area you believe was wet with 90%+ alcohol (70% is ok, but the other 30% is water..)
blow excess off with compressed air.
Preheat oven to near 100-125deg. May need to heat it to 200+ then turn off and insert board when oven reaches correct temp. you can just leave board in oven (on a cookie sheet an towel maybe) till its room temp.
Depends on how wet it got, but if it was a quick splash then this should dry everything, if you have ability 100deg for 24hrs is preferred.
hope this helps you, if not let me know i can try to help you revive the dead