Troubleshooting How can I revive my PW3?

I have just restored a winhex backup image to my Kindle PW3 and when it started it said: Device error wait until something happens but I failed to wait and just restarted by pressing the button for a few seconds (it worked on Keyboard) and now it sticks at the tree. Restarting by pressing the button for 40 seconds doesn't work. It just freezes at the tree.

Firmware: 5.9.6.1
(never jailbroken)

How can I solve this issue because I can't access the internal storage via usb at all.

Thanks.