the case is a hp 15-r260ne(la-b972p rev 1).
at first it didnt have screen after turning on.
i downloaded the bios from vlab links and replaced the bios.
now i have the screen but after 10 sec it turn off.
i tried many diffident bios from any where but nothing changed.please dont tell me about clear cmos or something like this.
i need real help if you can.