Hi: Three things I’d look at are: 1. do a water pressure test to make sure the tank is water-tight. 2. Have a look at the existing anode to make sure there is enough left to have been protecting the tank. 3. look in the combustion chamber to make sure you see no damage or evidence of water.
Beyond that, plan on replacing the relief valve. Also if you can find out, it would be nice to know what water pressure the tank has been exposed to. Higher pressure (anything 80 psi or more) can cause damage to the lining.