I recently purchased an att&t sx56. Unfortunately, I can't get the unit to power on. I read that the batteries on these are fickle so I gambled and purchased a replacement 1700 internal battery off ebay. I replaced the battery and the unit still wouldn't power on. I was about to give up when I tried a hard reset and presto! unit booted. I walked through the config to the point it asked me to insert the sim card. When I looked at the screen again it was blank and I've been unable to get it to boot since.

Any ideas what could be wrong? Should I be able to power the unit on if it's plugged into the wall (it doesn't power on when plugged in). I'm really anxious to see it boot just once more, help!