There are a few things that you can look for if you think your water heater fuse may be blown. First, check to see if the power to your water heater is still on. If it is, then the next thing you should do is check the thermostat to see if it's working properly. If the thermostat isn't working, then it's possible that the fuse has been blown. Finally, you can check the water heater itself for any signs of damage or corrosion.