I had to reinstall once to get it working however I have had reports of people reinstalling 4-5 times before finally getting it working.
If you somehow end up mid update with LauncherHijack enabled the easiest solution, assuming you can't get to settings, is to uninstall LauncherHijack through ADB (plenty of guides online) and reinstall it after you complete the update. There is nothing I can do without degrading the application during regular use. LauncherHijack causes issues during update 5.6.2.0, you wont brick your device or anything with it left enabled but you wont be able to complete update 5.6.2.0 until disabled. Please disable LauncherHijack in accessibility settings during Fire OS updates.
#SET HOME LAUNCHER KINDLE FIRE 5 APK#