The phone charger MIGHT have been left by a previous guest, but the key-card entry while he was off the premises is very interesting. And this is NBC, so we can believe it. /s
He could have left, then returned and temporarily parked outside and run back up to the room because he forgot something. I would be curious to see a more complete timeline synced up with the hotel's video footage of comings and goings.
That would have been removed by the cleaning people after the previous guest checked out.