There are a number of things that can go wrong – however your electric water heater has 220V in it be careful, not for the voltage but because your breaker panel will supply any short with a bundle of amps. So other than having someone else look at it, one thing you can check (with the power off) is check to see if the bottom of the tank is full of sediment. They really can fill up such that the lower element is overheating. If it won’t drain by the lower drain valve that’s a problem.