ROOT

[CavRic-1974]

I cannot log in to root using "su".
I have a dock for the PinePhone bought for $ 199.
Yes, I have keyboard to attach to the dock.

I downloaded the file

   Manjaro-ARM-xfce-pine64-lts-21.12.img.xz

But I don't know how to flashing it to my PinePhone.

I don't have an SD card.
On my PC I have the Linux Mint operating system.

I did an operating system upgrade but after about 1 minute it went into hibernation and stopped everything

Sounds like your OS installation got corrupted.
What's on my mind is to re-install the OS itself, although I wonder, is "gatto" an account you created by yourself?
Can you log into root using "su" (so without "sudo")?
Do you have a dock for the PinePhone/did you buy it at $149 or $199?
If yes (so if you have the $199 one), do you have a spare USB keyboard?