Chosen Solution
I bought a new NuPower (newertech) battery and installed it correctly, but when I was calibrating it (charging it 100% for the first time after it being drained completely) I had an emergency and had to leave with my laptop. It only had about half charge. When I was able to come back and continue charging, the charging cable light was green (to indicate 100% charge), but when I pressed the battery check on the side of the macbook it flashed to indicate it being 0%. I kept the cable plugged in and turned it on to see what was happening. It showed it has 0% and is charging. So I left it to charge for a few hours and it still showed 0%. No matter how much I charge it, it shows 0% and doesn’t work at all while not plugged in to charge. It’s as if there is no battery at all and is only working because of the electricity from the charging cable. I know I didn’t calibrate it properly, but I was wondering if there is any way to salvage and restore this new battery?
Drain it all the way down, like you did originally to calibrate then charge it up. It might also help to reset the SMC. Connect the power adapter to the Mac. On the MacBook / Pro’s keyboard, hold down the Shift+Control+Option keys and the Power button at the same time. Release all keys and the power button at the same time – the little light on the MagSafe adapter may change colors briefly to indicate the SMC has reset.
