I bought a used Pre 3 off ebay, it came with a stock battery and a Mugen. When I powered it up with the Mugen, it showed 98% charge. I wanted to fully charge it to use as a backup for my main Pre 3, but when I swapped the Mugen into the main Pre 3, it wouldn't power on. Connecting it to the charger got the ? icon. I tried it again in the newly acquired Pre 3, same result. I don't have the receipt, and would guess it's over 30 days-any tricks to get the battery functional or is this now useless? I have another Mugen and two stock batteries, but it never hurts to have another!