@mr_growl
userdata
yes formating /data to ext4 is required at first installation
Just in case maybe retry with fastboot
fastboot format:ext4 userdata
you can wipe cache partition too
fastboot format cache
What does dmesg -w return on your host computer ?
https://docs.ubports.com/en/latest/porting/build_and_boot/Boot_debug.html
To confirm that your device has booted correctly, on your host computer, run dmesg -w and watch for “GNU/Linux device” in the output. This confirms that you can establish an ssh connection to the device (see below). If you instead get something similar to “Halium initrd Failed to boot”, skip to telnet connection.