My Nokia C7 has stopped working.

For the second time my nokia C7 is in the service center. I was on my vacation in the Philippines when my nokia C7 has stopped working. The night before i was using my nokia C7's torch to light up my way going to the house of my sister, and because they do not have internet connection I used my nokia C7 as a modem for their netbook and yes it works really well. and then when I wake up in the morning my nokia C7 is dead. I tried everything to revive but nothings work to give back the power. Its still under warranty in the UAE so I decided not to fix it. I wait almost half month and when i get back to UAE i bring it to the shop... blah blah blah they take it and they repaired it. After one week that I am using it again it started to restart by itself until its lost again its power. Again I tried everything.. I removed the battery and put it again, I charged it but still there is no power. I waited one day charging and switching it on but no more. I decided to bring it back to the shop and they will fix it. On October 8 I'm going to pick it up... lets see. Now I have only the back cover, the silicon case, the batterry and micro SD.