Fine , assuming you have your bootlader unlocked already , go ahead ..
Download twrp 0623 for umi and put it in your adb folder..
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Download last android 10 , EU rom ..
Turn on usb debug from developer options..
Connect your phone to pc and copy the rom zip to storage ..
Delete all passwords and fingerpints if you have..
Enter fastboot mode and open a CMD ..
fastboot devices ( device recognition )..
fastboot flash recovery UMI_0623.img ( flashing twrp ) ..
fastboot reboot ( hold volume up and hit enter , hold volume up until you see twrp )..
Now you are on twrp ..
Choose , Reboot / Recovery .. ( phone will reboot to twrp again )..
Choose , Install / .. find the rom zip and swipe to confirm flash ..
When installation finish ..
Choose , Wipe cache and dalvik and swipe to confirm wipe ..
NOW , go back to main twrp menu and ...
Choose , Wipe ..
Choose , the right box to format data ..
Type yes and hit enter ..
Go back to main twrp menu and Reboot / System ..
Wait few minutes to boot ..
This is an easy way first installation method , i suggest this method for newbies , you can go on with this ..