Looking for any simple answers before I start digging.....

Battery was dead, so I charged it. Left the charger attached and opened door...had dome light and when I put the key in the dash was alive. Turned the key to on (not start) and everything died. No lights or power anywhere. Checked battery again and it shows charged. Main 80 amp fuse seems to be OK (haven't pulled it out yet to check with meter, but the view area where the fuse is supposed to melt is undamaged).

Anybody got any ideas? I'm looking for one of those simple common issues I guess. I don't even have a flicker of lights with the charger hooked up...to make sure there was at least some voltage available.