I have a 1994 deville and recently the battery cable went loose and the dash lights flashed on a off and then off and the key would start the car.

I jiggled the battery cable a bit and it started but now the dash lights intermettintly flash high and low and you can hear a clicking around and behind the head light switch and the emergency flashers cycle on a low beam as if "on" but they are not with the switch.

After you shurt the door they go off after about 20 seconds but if you re open the door the minute the door is opened they start cycling again.

maybe disconect boath battery cables and hold them together to let the capacitors discharge ?

but it really sounds like somethings shorted out somewhere

It sounds like the body module is protesting the loss/gain/loss/gain of battery. Pull the cables from the battery, clean as best you can, then reattach, making sure the post studs are tight. It's a 5/16 wrench. Connect the positive first, then the negative- this helps prevent welding a wrench to the fenderwell if you touch to ground. If they remain loose, or will not tighten, you'll need a new battery.