[Onetouch Idol 3 Android Development] mtek89:
2022 update: If anyone's looking to rescue their Alcatel Idol 3 from the restrictive 6.0.1 update without fastboot, the steps are surprisingly difficult to find (broken links everywhere), but easy to execute:

In a nutshell: Use adb to reboot into edl ("emergency download"), then use the edl tool to flash the boot partition with lk2nd (a boot image which allows fastboot again). From there flash whatever you want via fastboot.

Go into EDL mode:

via ADB:

Enable developer options (hit "build" in "About Phone" in settings 7 times, and then go to "Developer options" and tick the adb option.

Also tick unlock OEM while you're there.

Download and install android-tools on your laptop, and then do sudo adb devices -l. You might need to authenticate your laptop on the phone before this works.

After your device is listed in adb using the above command, do sudo adb reboot edl

The phone will vibrate and the screen will go black. This is EDL mode.

via Buttons:

With your phone switched off, plug a USB cable into it.

Wait for the battery icon to appear, then wait for it to vanish.

Once vanished, hold both volume buttons and power button together

Wait for the red screen, then press the volume up button and the screen should vanish. This is EDL mode

Install the edl tool:

If you're on arch linux:

You can just install the edl-git package from the AUR.

If you're not on arch linux:

Go to github and search for bkerler/edl

Follow the installation procedure

Get the lk2nd boot image:

Either get the latest image (highly recommended!):

Search for msm8916-mainline/lk2nd on github

Scroll down to "Supported Devices" to work out which release to download ("lk2nd-msm8916")

Go to the releases page and download the lk2nd-msm8916 image, which is compatible with the Alcatel Idol 3 device.

Or get the tried and tested Idol34_7_NPRG7627.bin image:

Search for the SUGAR QCT_SP v11.1.2 program. I can't link it otherwise this post will be flagged, but search for "Sugar" on xda for this device

Download and install the Sugar exe

After the install, go to c drive -> program files (x86) -> sugar -> tool, and search for the Idol34_7_NPRG7627.bin

If you have the larger idol 3 (5.5") then use the other bin

Use the edl tool to flash the boot partition of the device:

Ensure the phone is in EDL mode:

Go into EDL mode if you're not already. If the device isn't responding, then pull the cable, and hold the power button.

It should reboot after a few seconds.

Go into the EDL mode again following the instructions above.

Run sudo edl

This should tell you that it found the device, and that it found a bunch of loaders to upload and then it will exist

If you run the command again, it might not find the device again. This is normal, just ensure the phone is in EDL mode and reboot it if not.

Run sudo edl printgpt

This will give you a long list of partitions on the device.

One of them will be the boot partition. We will save a backup of this.

Run sudo edl r boot my-backup-boot.img

This will read the boot partition and write a copy of it to your laptop. This could be useful later if you want to restore the boot.

Run sudo edl w boot /path/to/your/lk2nd.bin (the file from step 3)

This will overwrite the boot partition on disk, with your selected lk2nd.

Reboot the device, either by sudo edl reset or just pulling the cable and holding the power button

The next boot will be fastboot, and you can run sudo fastboot devices to check that it works.

Next Possibilities (optional):

Installing PostmarketOS

Download and install pmbootstrap

Go to the postmarket OS wiki and search for installation instructions

Run pmboot init, and fill in the prompts with your data

Choose the "edge" release, when prompted, then "alcatel" then the 347 device

This may take some time to build

Put your phone into fastboot mode (as installed earlier using the lk2nd image)

Run pmboot install

This may take some time. After finishing it should ask you to run pmbootstrap flasher flash_rootfs.

Assuming no errors, run sudo fastboot reboot

If errors, see the troubleshooting section below

Troubleshooting:

"Help: Fastboot exists, but I can't flash anything to it:"

Problem: It keeps saying "remote: unknown command".

This is an issue related to fastboot being too old likely because you used the Idol34_7_NPRG7627.bin image.

Solution: Install the newer lk2nd image

Put the phone back into EDL mode via the manual button method.

You might need to hold the volume up button after the red screen for a few more seconds than usual

Download the latest lk2nd image for your device

Reflash via sudo edl w boot /path/to/your/lk2nd.bin

Yank the cable after the flash is complete, and power down by holding the power key

The next fastboot screen should actually be green and have text

"Help: I'm trying to install Postmarket OS but it fails at the last step:"

Problem: It keeps saying "remote: 'size too large'" after you tried running pmbootstrap flasher flash_rootfs

The system image you've chosen (e.g. Phosh) is too large for the root partition on the phone. You can try to chunk it:

pmbootstrap chroot

fastboot flash -S 64M system /home/pmos/rootfs/alcatel-idol346.img

But this will still likely fail.

A better option is to just install the system image to the user partition:

pmbootstrap flasher flash_rootfs --partition userdata

"Help: I can't boot Android anymore."

Problem: the SD card seems to take precedence in the boot order over the boot partition on the phone.

Solution: Completely remove the SD card and try booting again

If that still doesn't work, then follow the instructions from Vknecht's post