white screen after flash.... help plz

i flashed the phone of my friend just to try solve signal problem with stock rom of 3 file the phone is s7262 galaxy star pro duos
but i'm getting other problem like the white screen :(
when i'm traying to solve the white screen problem, in the first the bootlogo It was showing normal and then go to the screen white but now the bootlogo it's not shown clearly .... bootlogo white screen :crying: :crying: