I take it your water heater does not have the reset push buttons on the outside of the unit.
With that said as for the 110 mine stopped working, had to gain access to the rear of the heater. Once I could get to the rear of the unit there was a black plastic cover over the wiring and heater core. Check the wiring connections mine were burnt and close to starting a fire. Cleaned up the ends of the wire, reconnected with correct size wire nuts. Heater worked fine on 110.
As for your propane inspect and clean the tube outside, at times spiders or mud robbers like to call that home.
Retired and never looked back