On the back of the Level Best panel are the connectors. First step is to reset the controller. Disconnect the cables, all of them, wait a minute and reconnect. Easiest to do from underneath. The wires are tie wrapped behind the panel. (at least mine were). To test the membrane panel I suggest cutting the tie wraps and pull the controller by removing the 4 screws holding it to the dash. Cutting the tie wraps makes it a little bit easier. Next is the real pain.
On mine the membrane panel was attached to the housing with double back tape. Carefully take a knife ( I used a box cutter) and insert it between the membrane. DO NOT insert it more the 1/2 inch. If you do, you take a chance on cutting the connecting cable from the membrane to the control module.
I could not find a schematic anywhere. It appears they are using a microcontroller To actually run the system. On the control board there are several Driver transistors that I would assume are controlling the relays. The keypad is much like any other membrane keyboard and you could use a ohmmeter to check the buttons. I did not determine the pinout of the keyboard. I was more interested in the 3 amp fuse socketed on the control board. My was blown. My failure mode was that manual would work, but auto level failed.I did a webs search on parts and was able to find replacement modules and keypads so that is at least positive. Not cheap though.
Also, a good link in the large connector pinout.