Heating element comes on and stays on when not even called for.

There is a stuck relay or switch somewhere.

The important thing at this point is that you get it turned off!!!

Flip the breaker if you have to, but get it off, as it is a fire hazzard like that.

You can attempt to diagnose the problem yourself if you like and we can help. You will need a multimieter hat can read Volts, amps, and ohms.

If not, disconnect power and call a pro. But whatever you do, get it off ASAP.