Proper search queries for Google help a lot @geekmaster - U004 is great. Auto-translated from
http://www.siralex.info/2011/03/07/k...-update-errors :
Installation Errors on the Kindle 3 updates
Possible installation errors Kindle 3 update:
U000 (ERR_GENERAL) - General installation error
U001 (ERR_BUNDLE_VER) - upgrade version does not suit to this unit
U002 (ERR_BUNDLE_MD5) - Error checksum update file
U003 (ERR_IMAGE_MD5) - Error checksum of a file updates
U004 (ERR_UPDATE_MISSING) - any update files from the lost (damaged the interior of the update file)
U005 (ERR_UPDATE_TMPDIR) - Problems with the temporary folder tmp, for example is not enough space or upgrade program can not create a folder there
U006 (ERR_UPDATE_FAILED) - Update failed. Those. Update failed to update any of the files or failed to perform another operation. Typically, this means that some Kindle files were modified, for example if the set menu or the Russification of the virtual keyboard.
U007 (ERR_SIGNATURE_FAILED) - upgrade Authentication Failed. Each update signed certificate. Amazon signed his hacks in turn their own. If you install any hack and get this error, it means that you have not set JailBreak (or it is not working as it should).