Security problems?

[coconut_warrior]

Aloha,
I have a 2002 saturn L200. One day it would not shift into drive. Read the owners manual to override the issue. When getting home I undid the negitive battery cable to reset. Worked for a week. Again not going into drive. Negitive battey cable removed so many times I have lost count.Used and ODB II and no computer codes came up Also took to auto garage to make sure it was the same results and they came up with no codes. Now the lights flicker (inside and out) gas gauge reads E all the time parking lights stay on when the car is off and the key is out of the ignition , no dashboard lights, no automatic door locks, also the key can be removed from the ignition while car is going down the road or just sitting running. Binging noise on all the time as if a door or trunk is open, slaming drivers side door causes doors to lock and unlock by themselves. This car is driving me nuts ! after reading so much of "what could be wrong" I am looking for an answer to tell me what to do from the cheapest fix to the most expensive and in the order to do it. ( I have read about cables needing adjusting, fuses replaced, tumblers replaced, passlock sensors and BCM) I really want to fix this car as I have sunk so much money into it seems like a waste to just junk it. All suggestions would be welcomed with much Aloha!!!!
Mahalo
Coconut Warrior

[Ssicarman]

The key.
It is likely worn. get a new one cut from a key code at a GM dealer.

The binging noise.

Check the door switches. One is likely broken. Can't remember if the L-series has a pin switch or if it is in the door latch.

The rest of it sounds like the BCM is on the way out and then some.

[coconut_warrior]

Aloha Ssicarman,
Thank you so much for the reply. I'm going to get a key cut from the dealership and see if that will fix the problem. Checked all the fuses yesterday, all in good shape. Hope it is only the key as it is getting to be a real pain playing with the battery cables all the time.
Mahalo
coconut_warrior