As many unfortunate users of the MADE-IN-CHINA Vodafone Smart Ultra 6, i had the cursed boot loop with the "powered by android" message. And with a NEW, non-rooted, stock recovery - untouched phone with Android 6.0.1, and in the first days of LIGHT use.
The first times, after many tries (30 sec. power button press/reboot from recovery/connecting charger etc), the phone eventually powered on but in short amounts of time it keeps shutting down and the boot loop appeared again.
After two days of ZTE-anger, the phone won`t turn on at all with any tricks learn from the web.
The only thing that I could do with this s*** quality chinese phone was the following: I connect it to the charger and the phone was just bootlooping non-stop with the "powered by android" message.As soon as I was disconnecting the charger, the phone shutted down and nothing could convince the brick to powering on, any combination of buttons was futile.
In short terms, I could not power on the phone at all with just the battery (100% charged) and the stock recovery was not accesibile.The phone was 100% dead and only the charger could induce the continuous bootloop.
My personal conclusion was that if the phone was software-untouched/non-rooted/non modified in any way, the problem must be hardware.
And now, the possible answer - I dissasembled the phone with help from macbreakweeklyfan video (thanks, the phone is indeed very easy to open):
And I thought...what would be if i removed the battery?I proceeded to remove the 3 screws that are holding that metal Half-Life style crowbar that held the battery connector and atfer I disconnected the battery.
Then, I connected the phone with the charger, with the battery disconnected and surprise, the phone started up and it keeped to show fullscreen colors (red, blue, yellow etc) as in display-test softwares.It seems like a service test...something?
I disconnected the phone and connected the battery back, but without that metal-thingy and....the phone not only powered on from the first try but now, atfer 6 hours of use, seems rock-solid, without restarts and bootloopings.
The recovery works, powering on works, rebooting from menu works.
It seems that the problem is somehow, the battery connector and [probably] that piece of metal that pressed down directly on the wires of the battery connector. Maybe creating a short circuit/imperfect contact by the Hulk smashed wires?
I`m not saying that this is the definitive answer for all the problems with this Lo-Q, vaporware phone, but for me....it works (for now).
Thank you for reading this short story and sorry for the [many] mistakes, i`m not a native engrish speaker/writer.