It sounds as if you have a probplem with power-start by checking the battery cables and test for a loose of power at the fuse box in the gauge fuse and ignition fuse by hooiking a test light into it and watching it.It could wind up being a ignition switch.
Chevrolet Technician
33 years experience,24 years of Chevroler/GM experience and training .ASE Recertified Master Tech,