My laptop turns on but doesn't seem to boot neither the system nor the

My Lenovo 920-13ikb starts when I press the power button. The keyboard lights come on and the screen stays black but seems to be powered on because it lights up. I have tried pressing the Novo button but the process is the same. I have also tried disconnecting the battery from the motherboard and pressing the power button for 30s, but that doesn't work either.

Any ideas? Thanks in advance to all