Screen fades away after boot

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http://forum.xda-developers.com – Good Evening, I have a problem with the Xarc of my friend. When it boots it shows the normal bootscreen, but then it shows the homescreen for a millisecond and fades away. Then it reboots again, en so on. I have searched the forum about the same problem, but didn't find it. Also I have flashed the stock rom and kernel, different custom Roms with their kernels but all have the same problem, after the bootscreen the screen dies. The phone charges like normal with the battery-logo on screen. I started to think its maybe a hardware issue, but I wanna try here first, maybe someone (HowTos)