This sounds tome like you have a parasitic draw issue and it has killed your battery. Every time a vehicle battery is run completely dead it loses 1/3 of charging capacity. So if you run the battery completely dead 3 times, it is basically shot.Can you please take a voltage reading with a Digital Multi-meter [DMM] across the battery terminals. If you don't know how to use a DMM,here is a link below explaining how:
I have also included in the diagrams down below a guide on how to find parasitic draw in a vehicle. Please take the voltage reading and go through the parasitic draw guide and get back to us with what you are able to find out.
Images (Click to enlarge)
Saturday, November 30th, 2019 AT 10:15 AM