i want a new os on my kindle

[HedraXDA]

pretty much I just want fire os off and a new os on, how would i do that? here are some specs below:
Computer: Windows 10
Device: Fire HD8 5th Generation
OS Version: Fire OS 5.6.8.0 Build 626547120
Dev Mode Activations: adb (yes i have the platform manager to sideload a different version of fire os)
any tips would be greatly appreciated!

 

[TGRxda]

I'm in basically the same boat. Bumping this in hopes progress can be made.