Originally Posted by Ferchito
It is not a RANDOM thing. BLU published a software update and the phone tried to apply it automatically. The normal boot was modified by the update to boot into recovery (expecting to have the original recovery which would complete the update) but instead finding the TWRP which ignores the update (and the loop repeats).
Same thing happened on both my phones earlier today and I used the opportunity to investigate how to modify a recovery image
I created a new recovery with the proper partition info and now, after the update ran on your stock image, you should be able to install *this* TWRP and root again with SuperSU.
Here's the fixed TWRP:
I did it on my two phones and they are booting normally (and rooted of course)
Just install this one with the scatter file you already have and install SuperSU.
No need to even use Sideload, because now you can access all partitions normally from TWRP and the phone's internal storage from your computer.
Just copy the superSU zip to the phone and choose 'Install zip' from within TWRP.
The twrp file you have listed in your link works to boot recovery in twrp, however the new twrp file requires encryption. I have tried all working methods of side stepping the encryption that work on other devices. For example, I made sure to remove all screen locks, to none at all. This normally allows you to bypass the pin required to use twrp. Not In this instance though, even with no screen locks or pin in place the twrp file is still requiring a pin to decrypt trwp. I even tried setting a pin up for the screen lock, and when doing so the pin still fails to decrypt twrp. This renders twrp unusable.
Also, your previous method also fails, as twrp will not allow you to write to the device with the bootloader never being unlocked. The main issue preventing this phone from working with trwp is the bootloader. On my device the bootloader is un-named and fastboot will not allow the bootloader to be unlocked. I have tried everything possible to unlock the bootloader, and each time I am given the option to toggle the volume up key to unlock the bootloader and toggle down key to deny the bootloader unlock request. Unfortunately, volume up doesn't work, it's apparently disabled, so no matter how many times I press the up button nothing happens. The only options I have are to hit down bottom and deny the request, or let fatboot time out and it denies the request. My volume buttons work fine, so this is not a firmware issue, this is an issue with the ghetto, nameless bootloader the device comes with. I do have the oem unlock tab selected in Dev options too, so it's not a mistake on my end either. Hopefully someone will make an actual working breakthrough on this device.