Sounds like a blown fuse. Make sure you check the fuse on the back of the HU aswell as the ones under the dash and in the engine bay.

It would have been very easy for a fuse to blow if a wire was yanked out of the crossover. Think about it, the negative side of the power to the HU travels through the chassis of the car so if one of the speaker connections touches the chassis, you get a circuit between the -ve power run and the amp which shouldn't be there and pop goes your fuse you could also have gotten a short btwn the power running through the electric window mechanism and the HU..