I had this problem, stop charging PLUS won't start if not in R&D mode. I reflashed like 8 times, it wont'charge. I had to buy and spare charger and batterys. Like you said, the usb works for transfering data, but charging is what stop working. I want to try to dissasembly and try to see if I fix the usb but maybe I will make it worst, so.. Space charger and battery it is!