Hi Crazy Pierrot,
I have never heard of this issue, but I am willing to give some tips.
* You could try restoring your iPhone through iTunes
* If you dropped your phone for long periods of time, water could have seeped into the screen and/or logic board and damaged the compenents.
* If your phone is not working with any series of button combinations, I suggest you try and plug the phone in first, then do combonations.
I hope this will find you well
-With regards,
ziamaxim