That is why I am the advocate of an intermediate pressure relief valve in plumbing systems. Why would anyone rely on one valve if that is the result of its failure?
For the OP, that water heater is a POS unless you change the joke anode rod which is about 24" long, and aluminum. It should be a 45 or 54", you can cut them with an angle grinder to just reach the bottom. Magnesium is better and now you have a 15 year water heater. Also remove the JUNK 'drain' valve and put in a full port ball valve and drain it down a bit a few times a year. When I pulled the anode on my ge 6 year job, the anode was coated with pipe dope and metallic shavings.