[Lenovo ZUK Z2 (Plus) Questions & Answers] dancarriv:
Same problem, with a description

I am experiencing the same problem.

I bought this phone off someone, and it had the official indian firmware. I unlocked the bootloader, flashed TWRP, then flashed Mokee 7.1.1 and the phone worked great.

Then I got curious and started playing with the phone after I noticed issues with the GPS. What is did to get in this pickle is:

1- Reinstalled Indian official firmware (MM) qith QFIL, which was uneventful. When I set up the phone, I couldn't get OTAs, phone was being read as rooted (which was not);

2- Relocked the bootloader after flashing official Indian ROM (MM), was able to get OTA; Somehow, the phone still was being identified as rooted.

3- Again, with QFIL, I flashed official Chinese MM 1.9.063_ST. Uneventful again, the phone was completely back to stock, no root detected, all official status.

4- After this, once again, with QFIL, I flashed official Chinese Nougat 2.5.334_ST. Uneventful flashing, back to stock;

5- I installed Gapps via apk packages, got the phone to sync my calendar, contacts, etc. I was happy with this but noticed that the phone would not timely display notifications. I could have lived with this by manually checking the phone every now and then for gmail, hangouts, whatsapp, but noooooo, I had to get my hand into it again

6- I tried unlocking the bootloader again, but this time the phone would not be identified or seen by my computer, I could not open port 9008

7- I completely reinstalled windows 10, android studio, drivers (in that order), set up the PC to disable signature verification, etc. I was able to open the port 9008

8- I read on Zukfans that you could get proper Gapps integration by using/flashing Chinese MM 1.9.044_ST with QFIL, and then installing Gapps. I tried that, it worked at times, but still, notifications and sync were basically set to fetch, so I again went back to QFIL nougat chinese official ROM. All this time, the phone was working;

9- I decided to simply go back to Mokee 7.1.1, as it was the best experience I had on this phone. This time I could not unlock the bootloader, I could not open port 9008, and this after a fresh installation of windows 10 (I did try on windows 7 as well, nothing would open the port);

10- I rebooted to bootloader with adb command, and then I accidentally entered the diagnostics/engineering mode. I got the same screen that Człowiek`u posted in the picture and the phone has been stuck in it since;

11- I tried flashing again the official chinese nougat with QFIL and also MiFlash. The port would not open, and I was unable to turn off the phone. The only way I had to shut it down was to the the battery run out completely.

12- I finally used the deep flash method (peeling the charging cable and "short circuiting" the wires), and I finally got the 9008 port open, so I went back to flashing official MM with QFIL. The process worked, and upon restart, the screen would only display the ZUK logo for a few moments, to then simply start flickering black and white; I repeated the process with MiFlash, same result

13- Back to QFIL, this time with Nougat official. After opening the port with deep flash method, flash successfully only for the phone to boot automatically into the diagnostics/engineering mode screen (at least it didn't flicker this time). I repeated the process by using MiFlash, same result.

Does anyone here know of a way to hard reset the bootloader (I guess that's what I have to focus on) so that it does not enter the diagnostics/engineering mode automatically on reboot? Flashing with QFIL, MiFlash is successful, and it should reset everything to normal, but this keeps happening.

When I use the deep flash method for opening port 9008, the phone does go black screen as it should, and the tools correctly identify it as COM3, 4, etc with 9008 open, I get none of those Sahara errors, no 900E message. What can I do?