Look for a broken wire at the bottom of those switches. The common wire that runs to all of them.
Reseat the connectors at the bottom of the WPC board. While you're there, check the battery holder for corrosion. It is very common for corrosion to kill the self test switches.
If all looks OK, pull the connector for the self-test switches (see manual) and use a clip lead connected to ground to tap the header pin for ENTER. Be careful not to let the lead touch anything unintentionally.
Let us know what you discover,