Code:
Hit any key to stop autoboot: 0
Wrong Image Format for bootm command
ERROR: can't get kernel image!
uboot >
That error message usually means exactly what it says.
I don't see where you tested the image you transfered (which means it may be corrupted or bad in some other way).
So test the image file you are trying to use (the u-boot tools provide a decent image tester).
I don't see where you ever took the device out of fastboot mode.
You DO NOT reboot a device with the Kindle's USB cable plugged in, not unless you want to troubleshoot some really whonkey problems.
Unplug USB cable (the Kindle's normal external USB cable, not the serial-to-usb cable) prior to rebooting or otherwise doing any changes to the running system.
Read the battery report line -
Stop screwing with the Kindle -
Plug it into a wall charger until the battery recharges (should read: 4200 mV that is: 4.2 volt)