Success in reviving damaged batteries
Just going to report to all of you that I have managed to revive all of my "damaged" batteries. Been working on this for several days. I put each battery on the drone, turn on the drone and let the battery discharge until the drone shuts off. Then put the battery on the charger until the battery shuts off at full charge. Then put it back on the charger hours later (after it cools) until full charge. Then contrary to Autel's instruction, I put the battery back on the charger and hold the battery button for about 30 seconds then let it go. Autel says to hold the button 30 seconds while NOT connected to the charger and then connect it. The method of keeping it connected while doing the reset seems to be the trick to force the BMS to balance charge all the cells. I've had to do all these steps at least twice for each battery, discharge on the drone, fully charge, reset while on charger to balance charge. Then I test them on the drone while connected to the controller and the phone app to see the balance of the cells.
I have previously tried the method of battery reset while not connected then connect it to the charger and it has never worked for me. But now I have revived three damaged batteries and I got about an 18 or 19 minute flight this evening off of the worst battery. I'll try the other two batteries tomorrow. I have no other way to discharge these batteries other than put them on the drone and I only have the single battery charger so this has been a long and slow process but I am encouraged so far. I'm sure at some point these batteries will need to be rebuilt but for now I'm back in business with my older original batteries (almost three years old). I've got two new batteries but have never tried them yet.