F0 is a stuck key error
If as Gene says that with the keypad disconnected there is no error then the problem is probably the keypad.
Make sure the ribbon cable is seated correctly in the control board socket, if it is over to one side a bit could be a track is touching 2 connectors in the socket.
Clean the end of the ribbon cable with a pencil eraser. Do not use an ink eraser as it is too abrasive. Doubt this will help but it is worth a shot.
I could not find a wiring diagram of the keypad but it looks fairly simple.
You should be able to figure out which key is stuck closed with a meter.
Note that often they will use a common track on the keyboard for a number of keys re 2 or 3 and then a separate track for the other sides of the switches. Some electronics experience would help here.
I did find a service manual for the unit, unfortunately it was useless when it comes to this problem.
One interesting thing it did say is that some of the later keypads were held together with nuts, so you may be able to take it apart and clean/repair the stuck key.
Might be worth a try if you determine that the keyboard is at fault, after all you have nothing to loose at this point.