put jumper cables on a dead battery in reverse,, PCM is a failure.

So for members following this screw up , you put the jumper cable on the engine block on both vehicles ... then put the positive cable on the battery positive terminal.

battery drain can be a dead battery. another cause can be a interior lamp stays on .use a clamp on current meter current should be less than 20 ma .. if its above 200MA then pull fuses to find out what circuit is the cause.

junk yard PCM is cheap but you must put the proper PCM for your model year and vehicle..

door locks have diodes so because the jumper cables were reversed then the diode will short out.
door locks have coils and the diode stops the spike surge when the lock operates..
ac compressor clutch has a diode also .. relays also have diodes across the relay coil.
this could be a very expensive mess..

that is why I clamp on the jumper ground cable to the engine block ..