Diagnosing frequent trips on arc fault / ground fault (dual) breakers
Trip diagnostics a-la QO

The QO dual function and combination arc fault breakers use a somewhat peculiar procedure for trip reason readout, as detailed in the installation instructions:


Turn the breaker OFF.
Push and hold the TEST button for the remainder of the procedure
Start a stopwatch at the same time you turn the breaker back ON
Stop the stopwatch when the breaker trips:


Immediate trip: ground fault or arc to ground
Trip after 2s: arc fault
Trip after 5s: no fault or overcurrent/short circuit



Further diagnosis if this doesn't yield anything

If the diagnostic procedure above doesn't yield anything, I would turn the breaker ON with the culprit load plugged in and switched ON (running), but no other loads on the circuit, and then measure the time from turn-ON to breaker trip.  A fast trip (within a second or two) would indicate a short-circuit somewhere (bolted fault), while a slow trip (several seconds to minutes) would indicate that the load in question is overloading the circuit.

You can also try plugging the Keurig into a GFCI outlet on a different (non dual function protected) circuit and seeing if it trips the GFCI there; if it does, then it's definitely toast.  If you get an arc fault reading for the kitchen circuit, though, I would focus on the wiring as the source of the trouble; you can use classical "divide and conquer" troubleshooting to isolate the faulty wiring run if need be, by the way.