I have a diy flashlight with 6 18650 batteries in series. I charge each one of them separately with a TP4056 based charger. I accidentally, and very briefly, connected the + of one battery with the negative of an adjacent one (about 7V between them). Now the LED's are off and the charger's stuck at 3.74V at the output. What's the most obvious failed component, and can I fix it? If I can't, no big deal since they're dirt cheap, but it would be very beneficial if I could charge the remaining batteries in short order. Incidentally, if the batteries are at different voltages, but in series, I can still use the flashlight as long as I take into account the lowest charged batteries' capacity right?