First off, welcome to BonnevilleClub :P
Does the engine turn over? If so, VATS is not the issue, as it disables the starter and fuel pump.
I know that the PCMs on the '94 and '95 Bonnevilles are touchy, but not sure on the Rivs.
Your injectors might not actually be firing, causing the no start / no run problem. Someone here with more knowledge with that will chime in soon with a good way to check that out