zmaint sudo eopkg check | tee /dev/stderr | grep Broken | awk '{print $4}' | xargs sudo eopkg it --reinstall
after check
sometimes that is useless but eliminates the obvious. surprised there are no more replies on this Sunday, walks and talks and quacks like a boot problem. all other reading (yucky) suggests uuid mismatch.
but if you navigate thru the boot rescue section at Main Site that may fix things.
You are helping a friend who also has Solus, and has a problem...that is really cool. I hope you get more 2 cents before he comes to your house.