'custom OS installation' - cell not responding to either option.

i have galaxy grand prime. few days back i installed some updates but now my cell is not starting. its just showing the start screen samsung logo. when i press power key+vol down key+home key simultaneously, it shows 'custom OS installation' which on continuing never proceeds and on cancelling shows blank screen. i gave it to mobile repair center as well but it hardly connected to their server. can anyone help me out please. i have some data in my cellphone.