What I discovered so far about Nokia 2780

[Calyx Hikari]

The recovery mode can be entered with Volume Up + Hang Up/Power key, then to get the recovery menu, press Power + Volume Up. KaiOS 3.1 is now built based on Android 10 instead of 6.0.

In fastboot mode, technically the phone can be flashed with HMD Device Kit, and I can flash most of partitions, except config (for enabling OEM unlock).

I can flash cache-jb.img to this phone, but it still cannot enable developer menu. I wonder if I could use cache injection method to overwrite config partition with OEM unlock enabled flag? 

[minhduc-bui1]

Fabrice Desré—Chief Architect at KaiOS Technologies—confirmed that v3 now uses Android 10 as the base for Gonk, drastically improving app management. Apart from that, these should be documented under BananaHackers Wiki page for the 2780 Flip. Using HMD Device Kit to flash partitions on the 2780 Flip is an interesting method to me, and would suit as an alternative for beginners who aren't keen on using the traditional fastboot interface to overwrite the filesystem.

To get access to the Developer menu on the 2780 Flip, you can visit https://w2d.bananahackers.net on the phone's Browser and click on Launch developer menu; ADB will return as unauthorized and we haven't got any further than that. I don't think cache injection will allow permissions to overwrite /config in fastboot mode, maybe the location of /cache/__post_reset_cmd__ changed, but who's to say.

[Calyx Hikari]

Now I managed to achieve bootloader unlock of this phone.

Technically it should boot into arm32-binder64 Android GSI, but I was unable to boot into normal OS. 

Can provide pre-built images accordingly.

[ytagger]

How did you get credentials for HMD DeviceKit? Would be interested to see if this method would work for Nokia 2760