Check to see that the ribbon connector from the keyboard is properly seated into the circuit board. After unplugging power and flipping up the heater lid, remove the top housing with Torx wrenches. Lift up the front of the upper housing an inch or 2 to view the connector and reseat if necessary. If this doesn't help, order a new switch membrane from Ohaus. The old one can be peeled off and easily replaced with the new one.