[Al Skierkiewicz]

I am going to agree with Erik here. The LED comes on to indicate that a current path exists but that the breaker is open. Inserting a breaker and pushing it down to extinguish the LED sounds like you are forcing the board below the case or you are pushing down the board until the circuit path opens. I am betting you will find metal shavings on the board or underneath. Using a bright light, look into the WAGO connector and see if you see any crud in either of the ports before opening the PD.