[Xiaomi Redmi 3s ROMs, Kernels, Recoveries, & Other] ravisghosh:
Hi folks,

Finally I was able to flash Pixel Experience on Redmi 3s Prime. I faced many issues on the way and hence, I am putting them here if it may come handy to others. Here is the process I undertook and issues I faced.

1. Unlock Bootloader - This guide works fine - http://en.miui.com/thread-1513168-1-1.html

2. TWRP and Root - Used this guide - https://en.miui.com/thread-3293504-1-1.html

3. Download Pixel Experience and install from TWRP - https://download.pixelexperience.org/land

Problem with above method:

1. After I flashed Pixel Experience, I lost root access. Magisk was no longer installed to grant root access.

2. When I go back to TWRP, it asked for password, and no password worked. The data partition was encrypted and you cannot installing anything on it. Only way around to decrypt was factory reset and then reboot to recovery (not to system). Each time you boot into system / android GUI, data partition will be encrypted.

3. I did factory reset and reboot to recovery to reinstall Magisk or SuperSu. Now, data partition is not encrypted. But now, TWRP cannot find "/vendor" mount point. So, Magisk installation will fail with "Error 1".

4. I tried flashing stock boot.img from MIUI 10 and ended up being stuck bootloop.

Root Cause of the problems: The TWRP used in step 2 is not compatible with Pixel Experience. You need a different TWRP compatible with Treble as Pixel Experience Treble enabled.

RIGHT STEPS TO INSTALL PIXEL EXPERIENCE:

1. Unlock Bootloader - This guide works fine - http://en.miui.com/thread-1513168-1-1.html

2. Download Pixel Experience and put it in SD Card - https://download.pixelexperience.org/land

3. Download Magisk App (apk) and put in SD Card- https://******************/

3. Download Treble compatible TWRP "TWRP-3.2.3.0_Land-Treble.img" from https://xdaforums.com/xiaomi-redmi-3s/development/recovery-unofficial-twrp-xiaomi-redmi-t3701841

3. Install TWRP - Used this guide - https://en.miui.com/thread-3293504-1-1.html with few changes change:

(a) After you download TWRP.zip from above guide and unpack it, you will have a file twrp.img in the folder. Delete this twrp.img.

(b) Rename the TWRP-3.2.3.0_Land-Treble.img file downloaded in step 2 to twrp.img and place it in the TWRP folder.

(c) Switch Off Your Phone.

(d) Press Power Button + Volume Down to boot into Fastboot Mode.

(e) Connect your phone to your PC via USB Cable.

(f) Run the "Install TWRP.bat" and follow the process.

(d) Do not Reboot yet.

4. Install Pixel Experience

(a) While still in TWRP, go ahead and do factory reset.

(b) Install Pixel Experience that you have saved in SD Card.

(c) Reboot to system.

5. Root Access:

(a) Install Magisk Manager from the apk in the SD Card - Follow the guide https://en.miui.com/thread-3293504-1-1.html

(b) Open Magisk Manager and Download Magisk zip to flash.

(c) Power off.

(d) Reboot in recovery by pressing Vol Up+ Vol Down + Power together until MIUI logo appears.

(e) Flash Magisk zip from TWRP. Do not do factory reset, just wipe cache/dalvik should be fine.

IF YOU BRICK YOUR PHONE OR WANT TO START FROM SCRATCH:

Use this guide to flash stock recovery - http://en.miui.com/thread-1513168-1-1.html

Don't forget to check "clean all" instead of "clean all and lock" button, that way you need not unlock the bootloader again.

Hope this will help some people.