Also, for preventing updates (once everything is fixed):
There are two solutions.
- Reserving the update filename. Create this folder in the root of the Kindle userstore (otherwise known as the Kindle Drive. On Windows this is often "E:\" ** (, although I manually changed to "K:\" on my computer); on linux it is usually "/media/Kindle/"):
Code:
[userstore]/update.bin.tmp.partial/
The updater uses that as a temp download filename, but since it is a folder already, and the unix/linux command to delete a folder is different from the one to delete a file, the updater cannot figure out how to remove the folder to download the update to that location.
This no longer works on firmware >=5.6.0 -- Amazon noticed us. 
- Install the BackDoorLock hack, which will interrupt the updater process (but leave the update.bin on the Kindle, at least on non-touch devices).
** -- That's right, the one with the "documents" folder in it.
EDIT: Thanks eureka for pointing out the touch models do not download the update.
https://www.mobileread.com/forums/sho....php?p=2451671
EDIT2: I suggest you do both, just in case.
Amazon may "fix" the first one, or break the second, so use both as a failsafe.
It certainly cannot hurt.
EDIT3: What did I say?
They "fixed" it...