Ok, testing out 5.8.10 on my PW3.
No luck. It could be the KT3 as a difference
- Updated from 5.8.7 to 5.8.10
- Put update_voice_kindle_all_new_paperwhite.bin on usb
- Got the expected grayed out button
- Did a reset
- Waited until I was on language screen.
- Hit English, and waited.
- Got to the "Get Started" screen
- Plugged in USB
- Put factory file on the usb drive
- Ejected
- pressed "get started"
- pressed "connect to wifi"
- pressed the [x] to cancel wifi
- pressed "complete kindle setup later"
- pressed "yes" to confirm I wanted to complete registration later.
- pressed the [...] menu item
- pressed settings
- pressed the [...] menu item
- The update option was greyed out - womp womp
As an aside, the hotfix or the jailbreak remained. After doing the reset twice, I was still able to re-install my hotfix packege, which is signed with our jailbreak key.
Reminder - only tested on PW3 ( GO90 ), YMMV, Caveat Emptor, etc.