I was too lazy and tried to update from the terminal inside a KDE session. Big mistake! The system froze when installing VBox modules. There was no keyboard response so I had to make a hard shutdown. Tried rebooting... kernel 44 booted into rootfs but there was no keyboard response, kernel 41 booted into sddm but there was no keyboard response. Booting into emergency mode got no keyboard response, and changing usb port had no effect.
So, I burned a live image using another PC, chrooted into the system and tried updating again. There was nothing to do! Checking database and files had no error output. So, I tried reinstalling kernels without VBox modules. No effect!
I finally chrooted again into the system, cleaned the cache (except installed packages), and reinstalled all the packages from the cache. Rebooted again and everything seems to be there and working fine
Big thanks to all the devs and testers.
EDIT: had to rebuild megasync.