V5 Battery Firmware Download Error

So I was trying to update the firmware of all my V5 stuff, but was having a couple of issues when updating a certain battery. When the battery is unplugged, the first green light and the red light flash fast. When plugged into the brain, these same lights flash slow. The issue is that the firmware never actually downloads. The brain just flashes “waiting for download” for a couple of seconds every now and then. The brain then just turns off after a couple of minutes. We have tried to reset the battery, which didn’t help. We also tried updating a different battery, which worked fine, so the battery is at fault somehow.

Thanks for any help provided.

While I do not have a specific answer to this (running to my event in a minute) you can look up here for articles on debugging battery issues until a more informed answer comes: