@toniox EDL is different on Xiaomi devices. You have to use the MIFlash tool and use a MI account to log in (a complete f*&*&^$$ around to put it politely to get that done), then download the latest fastboot ROM for that device and I mean the latest fastboot ROM, unzip it and direct the MI flash tool to that. Hold Volume UP and Volume down together and plug the device into the PC and it has to be a Windows PC, MiFlash will not work otherwise, ensure you leave the bottom right box ticked for clean and install, do NOT lock the bootloader. Then start the process. If it fails, keep trying, it will work eventually. Unbricked my Mi A3 using this and it took a lot of attempts.
The other EDL mode is mutch the same, but requires opening the back, removing the mainboard cover and shorting the two EDL points, which requires fashioning a tool to do so so you can short the points and plug the USB cable in without requiring 4 pairs of hands.
EDL mode should work as it is the lowest point of entry to reflash the stock ROM and as the phone boots with that dialogue it should work.
What I cannot understand is an Xiaomi repair centre couldn't do this procedure! Any pro repair shop should be able to do this.
The other alternative is to buy a broken one and swap mainboards to get a functioning device.
It depends how far you want to take this.
