LIVE site -Support granted. Theme changed no site access

No idea what has happened.
No access to multisite.
Live site - granted support access - re theme - multilingual - post issue.
Site now shows WPMUDev theme not used for site or subsites including seperate SUBdomain holding jobs baord..
and has a WP update loop allowing no access to admin>
wp-admin - shows a preempt.. - wpts

O >>> M >>>>> G

Live site