Xiaomi has removed EDL feature on some recent MIUI ROMs including MIUI v7.3.x.x or above for Mi 5. Emergency Download mode (EDL) is in short a state when you can flash MIUI Fastboot ROM onto your device even its bootloader is locked. EDL mode has been so far a solution for those who want to unbrick their Xiaomi device without having to request for official bootloader unlock permission which usually takes days for Xiaomi to grant the permission. Unfortunately, Xiaomi development teams have decided to disabled EDL mode in MIUI 7.3 and therefore all latest versions above it.
Is there any alternative? Obviously! Meet Xiaomi Engineering cable, a solution of disabled EDL mode for your Xiaomi device. It is a special cable to bridge your device with your PC. Normally when your device is in OFF state, your PC will recognize it as a re-chargeable device and therefore your device will be charged with some juice from your PC. This Mi Deep Flash Cable will make your device recognized as flashable device instead. Once your phone is connected to your PC using this cable, port 9008 will open and hence you can proceed to flash MIUI ROM on it using Mi Flash tool.
Devices with locked bootloader like Mi 41, Mi 4c, Mi 4s, Mi 5, Redmi 3, Redmi Note 3, and so on, will most likely need this cable.
Mi Deep Flash USB Cable is basically available on many online stores like AliExpress for around $6.50. You can use Google to find out which stores you can buy such cable. However, if you have some time to spare you may also build your own homebrew deep flash cable.
Mitch002, one of MIUI moderators, have shared all needed steps to make your own DIY Deep Flash Cable using your phone’s existing USB cable, stranded chopper wire, twizer, plies, and tape. The process of making this cable is not too difficult as long as you pay attention closely to all steps he described.
There are all 11 steps you need to follow carefully to make your own DIY deep flash cable. You can read the original tutorial here or watch video below to watch a glance of what he did.
He also added that the cable works best if connected to a USB 2.0 port attached directly on the motherboard instead of the ones attached at the PC casing.
Once your PC recognizes your phone (but your phone is not in charging mode), you can then proceed to flash MIUI ROM on your device having locked bootloader. MIUI USB Deep Flash cable will help you bypass bootloader when flashing Fastboot ROM using Mi Flash tool. However, you may also need to firstly install Qualcomm QDLoader USB Drivers.