If you plan to put my firmware with saving data from any other (10.3.1.0 (based on Android Oreo) and below) or just want to test the firmware, then
BACKUP REQUIRED. 90% is sure that with data from the firmware based on the Android Pie, this firmware does not work. Any manipulations are made by you at your own risk. To flash the same as any firmware based on stock, so before this, familiarize yourself with all the necessary materials on flashing in this topic. I can only say that from any firmware MIUI 10 based on Android Oreo and any version of the firmware Masik (on the same android) you can move freely, checked personally. But, as he said, at his own risk, you never know.
All the necessary wipes installer makes itself (except wipe / DATA, here already at your discretion).
Do not forget about backup !!!Now, step by step:
1. Reboot to TWRP (I recommend
PitchBlack 3.3.1-PB-V2.9.0-OFFICIAL)
2. If you do not need to save your data (installed applications and system settings), then we make Vipe Data. To do this, select Wipe->Advanced Wipe, mark the DATA check mark and make the swipe below. If you want to try to save your user data, then skip this step.
3. Select Install, find the archive you downloaded with the firmware, choose it and make the swipe to the right.
4. In the installer, we all set up at your request, the explanations under items are.
Ready! You can restart the smartphone.
Setting Boot Restore in the default state leaves without change your current core, and the second item will install a clean kernel with a magic.
I recommend installing DPI equal to 410 (but taste and color, as they say, so experiment with the value in reasonable limits). To do this, go to the settings>Screen->The minimum width and here enter the desired value.
If after rebooting thumps all the time in the fastbut, then you can restore the performanceSo.