Both doors locked and unable to open?

I heard about this unfortunate situation. A 1991 928s4 was unable to get the doors opened with the key. Both sides. The only way to get in was via the hatch. Disconnecting the battery or the alarm did not help either. It turned out that the additional aftermarket alarm got into a malfunction condition and kept the door lock actuators powered for some time. That made the motors melt and get completely stuck, thus blocking the mechanism.
Replacing the motor assembly's was the only possible solution. btw: those of a 911 are the same.