Apple logo only shows when I pressing power button

When i remove the finger away from power button it goes back to black, and then i have to wait a few menutes and then i can do it again.

If i hold it for a time it goes black after about five seconds and i have to wait

If use power and home at the same time, apple logo shows for a few second, then it go black for a few second and then apple logo for new five seconds. Then it hust dead for a couple of minutes.

I tried to update it in itunes with cable. It makes the conection noises and still be black. When i start update it seems to work perfectly until an error comes up in itunes, and then we are back again :/ what to do?