If you were not plugged in the whole time, check your battery. If the brakes were engaged for any period of time in battery alone, it may be beyond saving.
Based on my own sad and expensive experience when a mischievous jerk pulled mine while it was in storage. Cost me two Trojan T-105s....
2019 K-2500 Duramax Crew Cab
2014 Silverback 33RL