to figure out the model, take a look for writing with black sharpie on the reel mech, the reel wiper boards and/or the lamp panel in the top compartment.
if you don't see anything, what is the code stamped into the slotted metal index disc on reel 1? Also, there's an M-645-xxx number on the payout counter disc.
I'd guess it's an 831 ... probably a later version one. Does your hopper have the plastic wiffle ball coin level detector in it?
the button you pushed is the safety delay mechanism. If the hopper motor is running but no coins are being ejected due to empty hopper or fault in the coin out detection, the game will eventually shut down completely. No lights except the red neon lamp next to the reset button.
a lot of the earlier games had a bar beneath the hopper with a red painted end you could push to reset the safety motor. Some later games got rid of the bar so you had to pull the hopper out to access the reset button.