Chosen Solution
Hi, My phone suddenly went down. I thought battery was low, so put him to charge without success. It won’t turn on nor charge (always black screen, no light). My external batterie detects the phone when connected, but the phone stays off and not charging. The battery seems pretty charged (3.3V on 3.8V) I tried VolUp+Home+Power, VolDown+Home+Power, VolUp+VolDown+Home+Power, but nothing happens… Is the motherboard dead ? repearable ?
To me, it sounds like the LCD is out. You could buy the LCD replacement but it would be more work than needed. If it were me in this situation, I would purchase a used Galaxy s3 mini of the same model as yours (since they are selling for around $30 to $40 online) and swap out the motherboards. That would allow to keep all your information and would only take about 10 to 15 minutes to swap them over. If this is the route you take, and you are still having the same issue, then the problem lies on the board.
hopefully the lcd is not out. i know for some strange reason phones will not charge or come on unless they are charged with the factory charger one that produces a whole lot of amps in charging. My suggestion is to see if maybe charging it with a more powerful charger can help out. i have had this problem with tablets before and that worked for me. I hope that this is helpful.
