EDL mode from fastboot mode MI Devices

by gsm on July 29, 2017

How to reboot to EDL from fastboot

Some firmwares support rebooting to Emergency Download (EDL) mode in Android Bootloader aboot module (the "reboot-edl" command) but fastboot utility doesn't recognize "reboot-edl" in the command line and refuses to send the command to the device.

Since FastBoot protocol is simple and text-based, it is enough to send a packet containing "reboot-edl" text over USB. The simplest way to do that is to patch Windows fastboot.exe file, replacing "reboot-bootloader" text with "reboot-edl". As "reboot-bootloader" string is found in the command line, fastboot.exe sends the same constant string to the device. So if "reboot-bootloader" is replaced with "reboot-edl", you can specify "reboot-edl" in the command line and the same text will be sent to the device.

I occasionally locked bootloader in my officially unlocked/rooted Xiaomi Redmi Note 3 Pro (Snapdragon) so it could only boot to FastBoot or Diagnostic 900E modes. Tried to swich from 900E to 9008 with QPST but it reported unspecified error.

Analyzing aboot (emmc_appsboot.mbn) found that it supports "reboot-edl" so the only thing remaining was to find a way to send it.

With patched fastboot.exe, successfully rebooted to EDL mode (9008) and re-flashed proper partition images
Therefore, to switch your half-bricked phone to EDL mode, you should do the following:

Download the attached ZIP archive and unpack it to an empty folder.
Boot the phone into FastBoot mode by holding both Volume Down and Power buttons until the bunny appears.
Connect the phone to the PC.
Double-click the "edl" (edl.cmd) file.
If the bunny disappears, your phone was rebooted and now should be in EDL mode (LED should flash red but not always).
Run MiFlash, wait 3-5 seconds and click "Refresh", COM port should appear in the list.
Proceed with MiFlash as described in the appropriate topics.