Stop demo mode

SOURCE: It says demo mode and there is no heat, everything else works

Have you checked your manual to see how to get out of demo mode? Since it is still in demo mode, you won't be able to use it for anything else. If you don't have the manual, go to GE's website and download the manual there. Also, you can check their site for Support and look for troubleshooting.

SOURCE: Microwave will not heat food. punch in heating time, press start and nothing happens

HI. your control board has failed. you will need to replace the control board asap if possible.

SOURCE: Bosch HMB 5050/01 Microwave -

Hi,

I'm assuming this is a built in oven/microwave combination since you mentioned the oven works fine. On a stand alone microwave, we would reset it by unplugging and waiting at least 10 seconds for the microwave to reset itself.
Was the circuit breaker tripped when you reset it? When you reset the circuit breaker, did you wait long enough. Try turning the breaker off, then waiting a couple of minutes before turning it back on. Then give the microwave a try.

Another thing we run into with a built-in is that sometimes there is not enough air circulation. Check to see that the vents are clear and clean.

Good luck! Reply back if this does not solve the problem.
If it does, I'd appreciate a 4 thumbs up. Thanks,

Handie Andie