2012 charger nothing electrical works.

2012 charger RT, I thought the battery was dead
so I hooked a charger up through the terminals
under the hood. After a couple of hours, still
nothing so I left it overnight. Next day, still nothing,
no door unlocking, no remote start. No interior
lights, the button does nothing when pushed.
Checking the battery under hood terminals, it
shows almost 13 volts. I get no clicking etc. Fuses
underhood all check ok. I was a mechanic in
another life, before computers took over
completely but I'm so lost on this modern stuff.