Battery, starter and alltinator is good.
How do you fix a car having no power from battery to vehicle? on 1995 Pontiac Grand Am
First you need to check the battery connections to the fuse box and the grounds to the engine, frame, & body. Check the main fuses in the fuse box, make sure they are not blown and bat+ is getting through them, for the beginning. Do you have a test probe, or VOM, to test power and grounds.