Thank you, thank you, thank you!!!
It booted now!
BTW, my last question (I hope!):
do I still need to do the last part of the fastboot instruction which says after one boots into SFOS to do:
Then update the bootloader via terminal…
[defaultuser@JollaC2 ~]$ devel-su
Password:
[root@JollaC2 defaultuser]# cp lk.bin /boot/lk.bin
[root@JollaC2 defaultuser]# /var/lib/platform-updates/flash-bootloader.sh