If you dont even get lights on the dash when you turn the key on, it has to the be 200 amp fuse in the box next to the battery OR you have SEVERLY corroded battery cables (and the far end of the battery ground cable has been an issue, it is hidden but corrodes.)

LOOKING at the 200 amp fuse won't tell you if it is blown, a simple check with a meter is all it takes to find that out.

This should be an easy one!