If your bootloader is unlocked you can flash stock rom via mi flash when you get in to fastboot mode.
https://en.miui.com/download-354.html Here is stock rom for mi a2 lite
https://yadi.sk/d/cel5Nm2sE1OpMg Here is the mi flash
Start the phone as fastboot mode (power and volume down)
Extract stock rom archive by right click and extract to folder
Move that extracted folder to desktop open mi flash and select that folder
Connect the phone to pc and click to refresh, select method "clean all"(installs system and stock recovery but doesn't lock bootloader) "clean all and lock"(installs system and stock recovery and locks bootloader)
and flash