'95 PA 3.8 engine trying to start itself

Basically what happened is as follows: my battery was dead, as I was hooking it up to an external power supply I heard a weird rattling kind of noise coming from somewhere under the engine (I was assuming it was the starter itself). This happened every time I tried to hook it up to an extra power source. Then suddenly the noise stopped and when I hooked it up to the external power supply again the engine looked like it was trying to start itself (without me turning the key).:screwy: Could there be a short circuit somewhere or did the starter itself short circuit or is there a third or fourth option... Bare in mind I live in a country where GM cars are mostly limited to Chevys and we do not have an official GM repair shop here so I do not have access to any kind of software/hardware with which to read any error messages... ANY help/ideas are most welcome.

Thanks,
tartukaru

my first thing i would look at is the starter solinod they can weld them self or a wire on the starter vibrated an is touching next time try tapping the starter with a hammer see if it dis engages

Disconnect the purple wire to the starter solenoid......now hook up the power source....if the starter still moves, then you know it's the starter solenoid....

If it doesn't, then you have either a short to power on this circuit, or if applicable, a stuck starter enable relay.....

I have seen this on my Buick.
I resolved it by charging the battery while off the circuit of the car (disconnected).
I can only guess the power levels or amperage is too low to allow proper system operation. In other words some of the power is charging the battery and some is trying to start the car.
During this it somehow activates the first relay to go to start on the starters bendix? relay.
Parking lot jumps were not very successful.