Aux Input brought upon problems

[MakuSoto]

I have a '03 x5 3.0i and I made my own aux input cable and connected to the rear 3 pin connector for my non-DSP, non-Nav radio and when connected without anything plugged into the female connecter the Aux does not show up from the MODE selections. When I do connect something to it, the MID screen goes blank but the radio still going for about 10-20 minutes and then turns off by itself. When I unplugged the aux cable, the MID goes back to normal.

At first, I thought it was the components problem and I tested each one for the correct values with a multitester and a capacitor tester with all being the correct values. Then I checked the placements and they were all correct as well. I went back to try it one more time with everything being checked and the same thing happens just like before, but this time the radio is permanently blank with the radio going on by itself and turning off after 10-20 minutes by itself.

I tried taking off all the fuses, the four fuses in the back and the 1 in the front glove compartment and waited a while before putting back in but that didn't help. After about 2 hours of trying again with the cable and the fuses, my battery seemed to have died out by itself. I did not keep the car on during the whole time, only when I wanted to test to see if the Aux would come up. It seems that somethings draining the battery by itself now after testing the Aux input cable.

Anyone have had this problem or know of a solution? Why the aux cable not working with it connected to the back 3 pin connector? (I don't know my radio version now that there's nothing to see on it at all, also all the buttons on the MID is non-responsive) How come the battery is draining? Is it because of the on-board computer is shocked/shorted from the aux cable?

Thanks in advance.