When I turn the key to try and start my GTP - everything shuts off. Dash lights, stereo, everything. Even when the car is on a jump starter - so it isn't the battery.

Also, the starter won't turn over at all - except when we jump the solenoid... Then the starter turns over, but the bend spring does not engage.

Additionally, the headlights flicker when the car is only on battery power - however they are fine when on the booster... Any thoughts on that?

I know there are a lot of questions, but there are a lot of problems - and I have no idea where to start.

Thanks in advance