The sound system is not "dead". Because it is part of the entire car's TheftLock, security, content theft, and serial data systems the car has locked itself. Ignition and fuel are disabled in the main PCM. The sound system must be restored to original and then the car needs to be unlocked by a dealership or GOOD autosound shop with access to the GM vehicle online database.
The reference to Crutchfield (Sound) is that they have all the advice and necessary harnesses, connectors, and jumpers to for sound system work on all these cars.
