Why would a Motorola a920 work fine for awhile and then all of a sudden everytime you turn it on it has a white light that says Motorola 3g and then turns itself off?

Most likely a bad bulb or corroded bulb socket. Next check your license plate bulb and socket. Check trailer hitch harness. Check owner's manual to see if there is more than one fuse box. It could...

well most people say turn off the light but you could say switch of the light.

Either you have a short or your circuit is severly overloaded. Either way call an electrician. It sounds like you have a fire hazard.

with the boom closed, press the on button, while holding it down, open the boom, and then it should stay lit and then pair. it just worked for me.

a light switch