[Blade Android Development] sbpetrack:
So I have finally succeeded to get root on my ZTE Blade A410, which behaved in an IDENTICAL manner to what you describe. Volume-UP has no effect, so can't confirm the bootloader unlock. The suggestion in this thread to do it with dd is also a non-starter. In fact, without root, you can't even mount the recovery partition, let alone modify it with dd. The Procedure took me about 30 minutes to do --- and about 3 solid weeks to figure out. I will give it in outline here, and then will give more detail in a separate thread. I guess it must be the case that there is a class of ZTE phones which just have a locked bootloader, and are not yet covered by previous posts.

To be crystal clear: I can root my phone, but I still cannot unlock the bootloader. I have posted to the mtk droid tools forum, hoping that someone there will be able to send me the read-backs I need to do that. In the meantime, here is how you root your locked ZTE Mediatek phone:

1. You need to get, create, download, or otherwise acquire a correct, well-formatted scatter file for your phone. If you have an older 32-bit Mediatek based ZTE, this is easy to do with MTK Droid Tools. If, like me, your phone has a newer 64-bit chip, you cannot use Droid Tools. But it's not hard to do. I found a scatter file for MT6735M online (that's the Mediatek in my phone). But I had to modify all of the addresses to match my phone exactly. I found the correct addresses in several places, and the fact that they all agreed was comforting: there was a badly formatted scatter file in the zte official update.zip ROM upgrade; I could do "adb cat /proc/emmc" without being root; and although Droid Tools was useless for my 64-bit chip, the debugging output log.txt prints out the entire partition table.

2. Armed with a good scatter file, you make what backup you can using SP Flash Tool. If you **** up, and you will, believe me, you will want these backups.

3. Now, you get a correct custom recovery.img for your phone.

4. And yes, it's scary, but you download that custom recovery.img over the one in your phone using SP Flash Tool. This is way below the level of anything that a locked bootloader or not-being-root can prevent. The phone won't know what hit it.

5.Voila -- you now have a phone with TWRP or CWM recovery. And **it** just doesn't care if you are bootloader-locked, or S-ON. It will let you flash the correct supersu.zip file to your phone. When you do this, you will be rooted. If you want t STAY rooted, then before you reboot normally, or shutdown, you MUST reboot once back into the recovery you just installed -- and let the recovery modify the system partition as it wishes. Once you do this, you will be permanently rooted.

But your bootloader will be as impregnably locked as before, I'm sorry to say.

I was truly an android virgin before I began this exercise about a month ago. My phone and I have been through a lot together since then. I only say this to give you confidence that you shouldn't be afraid to do this -- but you really SHOULD make sure you understand the steps before you do, or you really might regret it. I know i was annoyed when I discovered that I had replaced my recovery partition by an unbroken sequence of 0s (the first time I tried to flash the custom recovery). But i had read though the SP Flash Tools tutorial and got past this. I'll be happy to give more detail to anyone who needs it.