[Miscellaneous Android Development] greatbal:
I bought a Nextbook Ares 8 whose stock rom is:

Model : NXA8QC116

Android Version : 5.1.1

Build # : V2.0.3

Kernel version : 3.10.62-x86_64_byt

As with all of my Android devices, I always have to have a custom recovery and device must be rooted.

And upon googling around, there's not much discussions/forums in installing custom recovery and root for this device.

I came across @vampirefo's Root Nextbook Ares 8, TWRP Recovery, Disable encryption

His thread is specifically for the Nextbook Ares 8 with stock Android 5.0. But, despite his warning, as I really needed TWRP and root, I went ahead and did his steps. I was successful in installing TWRP. But, unfortunately, his modified boot.img did not work with my Ares 8 5.1.1 stock rom. My tablet was stuck in the Nextbook logo.

Good thing is I made a TWRP backup of my stock 5.1 rom, including the original boot.img. Unfortunately too, the stock boot.img won't work with unlocked bootloader. Still bootloop.

So I edited the original 5.1 boot.img so it works on unlocked bootloader/custom recovery. I also modified it to remove the force encryption.

I flashed my modified boot.img and my Ares 8 booted normally. So i am happy with TWRP installed and a rooted Stock Ares 8 5.1.1 rom. :)

I am posting here the modified boot.img (with encryption removed) and a TWRP backup of the Rooted and Unencrypted Stock 5.1 rom so others may try (at their own risk).

Requirements:

1) Nextbook Ares 8 with 5.1.1 stock rom. NOTE: The modified boot.img attached is for the stock 5.1.1 It won't work properly with other roms. If you are using a custom rom at the moment, go back to your TWRP backup of stock 5.1.1. If you don't have a backup, you could try the TWRP 5.1.1 backup posted below.

2) TWRP installed (using @vampirefo's method)

IMPORTANT NOTE: Make a backup of all your important data. Unencrypting your device will wipe your data partition.

Steps:

1) Read disclaimer above. If you're ok with that, go to step 2. Else, leave this thread, and go elsewhere. :P

2) Head over to @vampirefo's thread to install TWRP. Root Nextbook Ares 8, TWRP Recovery, Disable encryption

3) Don't reboot your device as the unmodified stock boot.img wouldn't work with unlocked bootloader and @vampirefo's modified boot.img will not work with our stock 5.1.1 rom.

4) Boot to TWRP. Making a system backup is highly recommended (but not necessary).

5) Download, place on your sd card and install via TWRP the attached file Ares8_5.1_modified_boot.img.by.greatbal.zip (just like a normal zip file flashable via TWRP)

6) Reboot your device after successful installation.

7) Enjoy. :)

Suggestion:

Install SuperSU via TWRP for a better Android experience. :p

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TWRP Backup of Stock 5.1.1 Rom

This is the TWRP backup of the stock Ares 8 5.1.1 rom. It's pre-rooted and removed force encryption. It's working on my device. You could try it on your Ares 8 version.

Steps:

1) Download Ares8_Stock_5.1_rooted_unencrypted.2016-11-08--TWRPbackup.zip

2) Extract the zip file.

3) Transfer the Ares8_Stock_5.1_rooted_unencrypted.2016-11-08--TWRPbackup folder you extracted to your sd card. Place it inside the TWRP/Backups/[Your Device] folder. Mine it's TWRP/BACKUPS/NXA8QC116/ folder.

4) Boot to TWRP.

5) In TWRP: Wipe>Advanced Wipe. Wipe dalvik-cache, cache, data, system.

6) In TWRP: Restore>Choose "Ares8_Stock_5.1_rooted_unencrypted.2016-11-08--TWRPbackup"

7) Reboot after successful restoration.

NOTE: the TWRP backup already has the modified boot.img, so you don't have to install the Ares8_5.1_modified_boot.img.by.greatbal.zip

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Credit goes to @vampirefo for his work in bringing TWRP and root to Nextbook Ares 8. :)