For the water heater to fail in both gas and electric modes, it would seem like:
1) As Dave suggested, you have it in bypass mode (and if empty, have probably burned out the electric element)
2) You have 2 separate failures; perhaps a burned out electric element, and a different problem on the gas side
3) Something caused the water to get too hot, tripping the Electric Cut Out (ECO) switches on both circuits. That's where the reset buttons Dave mentioned come into play.
In the schematic, the 110V circuit is very simple. If you have both switches on (btw, the one inside should be lit up or you have a loose wire or another power issue on that circuit), the power then flows through the thermostat and the ECO. If the water gets too hot, and the thermostat fails to open the circuit to shut off power to the heating element, the ECO acts as a backup, opening the circuit and keeping it open until manually reset. This is a safety feature.
If pushing the reset button allows the heater to function again, you need to be cautious because the ECO shouldn't trip unless the thermostat has failed. It could fail again.