HiCustomerI just took a look at the wiring diagram for your fridge. There really isn't much that could be affecting this other then the board. Start over. Even though I know you checked it, undo everything, and reconnect it. Make sure your grounds are connected right. It just seems kind of odd that it would happen to two boards in a row.
This really seems like a wiring problem. Also, the not defrosting problem could be the defrost thermostat. You need to get a reading when the unit is cold. In fact, it should be closed at this point, but it should open when it is cold enough. If it doesn't, then that is where your original problem is.I hope this helps. If it does, please click accept. If not, please continue to ask and post symptoms. If you do accept, please leave me feedback so that I know how I am doing. Thank you!