Hi, we have a norcold n621 in our camper. When we bought it the on/off button would not work-fridge was on all the time unless we disconnected the battery cables. Then after unplugging and replugging this last time we have no display on the front control panel. Nothing works-not even light inside. We replaced the front circuit board and are still getting nothing. The back circuit board has 2 fuses and both look good. There is a small discolored spot on the back circuit board. We were wondering if anyone has any experience with these. We hate to keep throwing money at this if that is not the problem. Thanks for any suggestions!