Make sure the lead wires and terminals on the switches and potentiometers are not shorting out with the shield in the cavity. Often after tightening the controls, small bits of wire and solder can short out the controls. If you unsoldered the components so they could be removed, there is a chance the solder dripped under the terminals of the potentiometers. This can happen when re-soldering the pickups or hookup wires. And make sure the wires are connected in the right place.