Thanks for all the tips. Managed to upgrade the device to 16.04/stable.

Thanks for all the tips. Managed to upgrade the device to 16.04/stable.

@Stefano @Lakotaubp Newbie here and aware of the holiday period so I do not expect elaborate answers. But I see mention of twrp; can anyone explain what that is?
Also, @Stefano your command "sudo fastboot flash recovery recovery-turbo.img" I can just issue from Ubuntu terminal on desktop computer and it will automatically find the phone (when connected) and reflash my device?

I tried both options:

• Power + volume up gives me a new screen with purple background and (I guess) Ubuntu logo.
  But nothing happens in the ubports-installer.
• Power + volume down give me the Meizo powered by Ubuntu screen with underneath the message
  PSN: xxxxxx
  => Fastboot mode (unlocked, unrooted).
  Again, nothing happens then in the ubports-installer.

I cannot find instructions anywhere on how to upgrade an out of the box Meizo 5 Pro Ubuntu Edition to ubports. I find a lot of info on how to do this for an Meizo 5 Pro running Android but that is not applicable.
When using the ubports-installer, nothing really happens after my device is recognized and I press 'Switch to UBports. I see the phone switching into a different screen but the ubports-installer is reporting "Adb push error: device not found"

Anyone can help me out here.

B.t.w. is there somewhere documentation on the Meizo 5 Pro Ubuntu Edition online available?

Thanks!