If you have same problem, try these procedures:
1) Remove battery
2) Put the battery back (do not switch on)
3) Press Red, Green (actually they are grey because the phone is still switch off) and Camera buttons simutaneously and do not release.
4) Use any available finger to press the power button, so 4 buttons is being pressed
5) Now, screen lights up, then blue logo comes, then the 2 hands finally come back and shake.
But it is not good because:
1) all personalised settings lost
2) all contacts lost
3) some apps will be automatically reinstalled again like nokia music
4) some apps downloaded from ovi store lost
There may be other problems. If you don’t think they are problems, you still can keep using the x6 along with the 4-buttons-hard-reset.