Quoted from robertmee:

If both of the above checkout, another test, is with game off, J7 removed, DVM on ohms/continuity, put red lead on Pin 1 of the J7 connector, and then check Pins 2 through 10 with the black lead, and see if you have 0 ohms on any pin. This would indicate a shorted socket or flasher bulb.

Quoted from RVApinballer:

For your ST, Id imagine either your transistor went bad, or somehow you lost a diode on the coil or coil is shorted. My money would be on the transistor. Been known to happen even on newer games like this. Any chance it was while you were holding a flipper button in for a while cradling the ball? Failure could happen a number of ways but that seems to do it sometimes. Easy enough to test and replace a transistor on a SAM game. I'm not an experienced tech guy and did this successfully.
I will say though, get some help soldering if it's your first time. Once you put a new transistor in you probably won't have another problem with that flipper as aftermarket transistors from pinball life are more robust.