I had the same problem with my m55, and still have it. My mobile is being repaired by technicians but I'm afraid it's a hardware problem. I have been told that it's because of one burnt transistor that what makes is just the opposite to charge, i mean, the transistor discharge the battery. But be in contact with, when I receive back my mobile I will answer what was the problem and if I was told it I would tell you. However, be patient, you know how the technicians are....
