On a GE microwave F3 means you have a failed keypad.
We replace these for customers nationwide with our guaranteed $39.95 service.
If you might want to replace it yourself, I have uploaded a handy guide
with pictures showing you what's typically involved. It's
here.
Please feel free to contact me directly if you need more help.
We're happy to help and we appreciate your thoughtful rating of our answer.
William E. Miller, AS-EET
[email protected]
http://www.microwavedisplay.com