Hey I have a 1990 gmc gypsy s-15 and I just got it and I have no power in the cab or anything except my headlights and tail lights and the back glass release I replaced my ignition tumbler and my ignition switch and still have nothing in the cab I can’t even see if it turns over or not I also changed my ground too the battery and power wire too the starter

 

All I can offer is general advice:

Have you checked all the fuses? In the second gen Blazers there are fuses in the passenger compartment and the engine compartment. There are also relays in both places too that may be part of the affected electrical systems.

Perhaps someone with a wiring diagram can help out.

 

Ive checked the fuse box and i checked the relays that are in the engine bay and 2 of them are toast but I think those are for the starter and fuel pump but I don’t see any relays in the cab tho