One of the functions of the test point is to repair the device. On Qualcomm-based Xiaomi phones, we can bring the phone to EDL Mode to do the flashing. Another way to update the firmware without going through Fastboot when the bootloader is locked.
You can find a test point on the surface of the mainboard. I will share pictures as a guide. Connect the two test points correctly and look at Ports in the Windows Device Manager. Make sure you find the Qualcomm HS-USB QDLoader 9008. Then you can update the firmware using the Qualcomm flash tool.
Note, some Xiaomi devices require an authorized ID.
Xiaomi Redmi Note 4X Qualcomm Snapdragon (MIDO)
Xiaomi Redmi Note 5A (UGGLITE)
Xiaomi Redmi Note 5 Pro (WHYRED)
Xiaomi Redmi S2 (YSL)
Xiaomi Redmi Note 7 (Lavender)