This might be a bit off-topic considering the debricking method mentioned here, but this seems like the best place to post it.
A few times, I've bricked my kindle (5.12) and come accros an unusal debricking method. This is for when your kindle is stuck at the tree screen.
1.Do a hard reset. If this makes any change to the screen, do it again. Repeat until nothing interesting happens.
2. Hold the home button and the power button down simultaneously for 20 seconds. Repeat until nothing happens to the screen.
3. Repeat step 1.
4. Repeat step 2.
5. Blah blah blah.
If this doesn't work for you, maybe my kindle's just weird.