It sure sounds like your electric side of the water heater is not working at all. It sure helps if you tell us the year and model of your Montana. The best idea is to put that info in your Signature which you can create via the User CP pull down in the second brown ribbon above.
There are two troubleshooting manuals in the Files section. They should give you a good start on finding the problem.
https://www.montanaowners.com/forums...?do=file&id=57
https://www.montanaowners.com/forums...?do=file&id=56
The most common problem is a burned out (due to being on with no water present) heating element. Second is the black rocker switch in the lower left corner being OFF or burned out.