[Lenovo ZUK Z2 (Plus) Questions & Answers] saurav_k:
Hi Friends

I have been using crDroid 7.1.2 on Zuk Z2 plus for last 1 year almost. Tried a few ROMs at that time and settled with crDroid. Did not get much time after that due to hectic work schedules.

Now, I am planning to upgrade to a stable Oreo Rom. AEX and Jaguar seem most popular, but I would experiment with few others like crDroid as well.

However, I have few concerns and doubts where I would request your guidance and help. I did some research myself and went through lot of threads but still some questions remain:

1) I face two irritating issues on my phone. Not sure if it is a device issue or ROM or baseband issue:

a) While on speaker on a call, the person on the other side cannot hear me clearly. My voice is extremely distorted.

b) Same happens on call recordings even without being on speaker. My voice is totally distorted in all call recordings.

So, someone suggested me to update baseband by flashing ZUI 1.9 and subsequent versions. My current baseband is 1.76 Indian. Multiple doubts on how to go about doing this safely and efficiently:

a) Do I need to flash complete Chinese ZUI ROMs in this sequence? 1.9 -> 3.5 -> 4.0? Does the 4.0 ZUI support VoLTE?

b) How to flash these, QPST, TWRP, QFIL - See different options mentioned in different threads.

c) Also, saw some directly flashable baseband zips without the need to flash ZUIs or to flash baseband 1.70 chinese first.

https://xdaforums.com/lenovo-zuk-z2/how-to/zui-oreo-firmwarebaseband-twrp-flashable-t3776254

https://xdaforums.com/lenovo-zuk-z2/how-to/baseband-radiomodem-z2-plus-twrp-t3749988

https://xdaforums.com/showpost.php?p=75584934&postcount=9

Which is the latest and most stable baseband version. I understood that the baseband version number doesn't change but there are updates on each version of ZUI.

How to fallback to 1.76 Indian baseband in case something goes wrong.

Please suggest what is the best and safest approach. Not much awareness of usage of QPST, QFIL etc. Used TWRP before for flashing ROMs. Do not want to end up bricking my device.

2) If I flash these Chinese ZUI ROMs, I guess the bootloader will be relocked? I have the unlock_bootloader.img which I originally used to unlock the bootloader. Guess, that can be reused to unlock it again. Just wanted to confirm, no other complications here?

3) About Treble and Non Treble TWRPs and ROMs, which one is preferable? After flashing the Chinese ZUIs or directly flashing latest Basebands depending on outcome of point 1, I believe I will have to flash the latest TWRP (Treble / Non Treble). Also, accordingly I believe I will need to change the partition name: Factory2Vendor ?

4) Which ROM and Kernel combination would you suggest. Priorities are No bugs, good Battery life, VoLTE, Less heating, Smooth UI and customizations like in AEX / crDroid / RR etc. Gaming is not priority.

Also, in my current crDroid Nougat, although Magisk Hide, hides the root from most apps but some apps like Google Tez, Microsoft Intune Company portal etc detect the root and does not allow usage. I need to have my official mailbox setup via Microsoft Company portal and Outlook. Which is not allowed on crDroid Nougat with Magisk but works fine on my Moto G running on Lineage OS 7.1.2 (Unrooted).

5) Finally, anything else which I might be missing or not considering? Please suggest me high level steps for the above. Specially for point 1.

Kindly help.

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