MrBeast
Explorer
The first thing you need to do is find out if you have 12v at the bulb socket or not, use a ground that is not part of that circuit, IE ground directly to the body, like at the door striker.
If you do not have voltage there the next place to check is at the switch to see if it is supplying power to the dome light circuit.
If you do not have voltage there the next place to check is at the switch to see if it is supplying power to the dome light circuit.