Sounds like one of your power wires shorted somewhere, did you make sure the orange, yellow, red, and the amp turn on wires were not getting grounded somewhere?
Inspect them at the wiring harness, I'd disconnect the battery cable while you are doing so, in fact it would have been a good idea for you to do so when you were removing the deck to inspect it.
Never heard of a battery going instantly dead from a brief short, so you may want to have the battery tested to see if it is still good.