Hello! Got an 820-3787 here with a strange symptom! It was not turning on. I found a shorted cap near J5250 area, cleaned the area and replaced the cap and the board tuned on. No corrosion at all nowhere over the board but the J5250 area. I replaced the battery with a new one because the original was swollen. Gave back the machine to the costumer. 10 days after he returned and the battery was not recognized anymore. Sent the battery to RMA and got a replacement. The replacement did not even work. Sent it back again to RMA and today I received the new one. I put it on the machine again and the machine started with the new battery. Thought the problem was solved. Glued the battery into the machine and assembled the computer again. When I tried to turn it on the machine did not recognize the battery again and the OS says to replace the battery immediately. If I remove the magsafe charger the machine dies immediately and does not charge the battery. Any ideas on where to start? It's very unlikely that I got 3 bad batteries with the same defect!