there is DQ15-N5110 after boot and DELL Logo load restarts continuously. I use this file download/file.php?id=24262 and dell website own bios file extracted from bios updater .exe file, but nothing changed. If you press and goes to bios no restarts happens! just after POST restarts begins.

nobody have idea? when brought this laptop it is powered off. many ICs changed by new one ( isl,apl) but now this is big mistake.

Check Ram, HDD and LAN CARD

I changed RAM, there is no HDD, There is no Lan Card ( if you mean WLAN).

Finally, its from cpu core PWM IC(isl). there is some caps moved around during soldering ISL! after correct it, everything works OK.