Here is a parts breakdown using JTP15AA2AA GE JTP15AA2AA
Sounds like a bad connection
Unplug the unit and open up the control console
I would check/clean the power in cable to the control board first since you are loosing power.
Remove ribbon cable from keyboard to control board
Check the cable's conductors for hairline cracks, a magnifying glass helps
Clean end of ribbon cable with a pencil eraser (not ink as this is too abrasive)
Remove other plugs from control board
Check pins for discoloration often a brown coating
Clean all plugs and receptacles using electronics contact cleaner or isopropyl alcohol and a toothbrush.
Make sure all are good and dry before reassembly
Put her back together and give her a shot
You may also have a cold solder joint or cracked copper track to one of the components on the board.
The board will have to be removed from the stove and then from it's frame so you can see the soldered side. Then with a magnifying glass check all the soldering, cold joints are usually duller in colour and/or may have pin holes. Also gently wiggle the components while looking at it's solder points often you can see the components leg move in the solder re: it's loose.
Can be a royal pain to find and I have resorted to re-soldering a good portion of a board when nothing showed up visually. | 
