someone will come up with a far better answer than me, however,

*check all fuses, check coindoor switch n buttons arent jammed in, and try to disconnect that one solenoid to see if the game starts up.

*If u can disconnect that one solenoid without cutting wires, look at your manual and remove the plug on the main board that runs the solenoids, this shld allow the game to then start up at least. I am hoping the semi locked on coil is only a switch and it hasnt travelled back to the main board.
If this doesnt work, disconnect all switches from game by again removing relevant switch matrix plug on main board.
I know this works on other brands, and i cant see a Stern being any different.