Nokia 8110 4G

Nokia 8110 4G, is a KaiOS device released in February 2018.

Shortcut to EDL
Keep both the up and down key on D-pad pressed, and connect the powered off phone to PC.

EDL cable can be also used.

About Fastboot mode
Nokia 8110 4G and possibly other two KaiOS devices actually have Fastboot mode, but have to be triggered by tampering either boot or recovery. It also proved there's bootloader lock state. This method is discovered by Dylanmurz.

Bootloader Unlock
Now to unlock the bootloader, we need to use the HCTSW_ARG-unlock_pkg (will be added later) and flash it via EDL mode. Note this package is specifically for Nokia 8110 4G and cannot be used by other models.

Connect the phone to EDL mode according to the shortcut forementioned, then remove the battery once triggered.

For Windows users, make sure the driver is indicated as "Qualcomm HS-USB QDLoader 9008" in device manager before you flash, then use QFIL to load the firehose file and the rawprogram0_arg.xml only to flash them.

For macOS or Linux users, you may want to use the EDL.py script. ./edl.py xml rawprogram0_arg.xml --loader=/path/to/prog_emmc_firehose_8909_ddr.mbn

After flashed, disconnect the phone, and press both volume up key and power key to boot the phone. Release both keys after 10 seconds, then connect the phone to PC.

You can now unlock it with these commands: fastboot flashing unlock_critical fastboot oem unlock-go fastboot reboot

Since recovery is tampered, bootloader unlock won't erase userdata immediately. However, due to the existence of recovery-from-boot.p in stock OS, the recovery itself will be recovered - when you reboot to recovery again, the userdata erasing procedure will be triggered.

Temporarily Rooting
This is mainly the work of Bananahackers.