So…
We had a structure in abandoned state
→ somebody put it into hull timer
→ we fueled it
→ we successfully defended the structure timer
→ the structure went through the repair circle, repped up.
→ we leave.
next morning : the structure had its hull taken off and accordingly exploded.
What did go wrong ?
"Onlining a service module in a structure that is in the Abandoned state will return it to Full Power, restoring its abilities provided that the structure is not damaged, as service modules cannot be onlined for a damaged structure.
If a structure survives through a Hull Vulnerable repair cycle and transitions back to the Shield Vulnerable phase, then the service modules will automatically attempt to re-online themselves, provided there is fuel available to do so."
Was it fueled or did you actually turn on a service? Judging by your above list, you did not turn on a service. The modules probably did not turn on automatically for some reason.
Yeah it was fueled. AFAIK our CEO of hearts did not manually re-online but… “If a structure survives through a Hull Vulnerable repair cycle and transitions back to the Shield Vulnerable phase, then the service modules will automatically attempt to re-online themselves, provided there is fuel available to do so.”"
You had better checked that before leaving. I guess the modules only turn back on if they were online before the structure went into abandoned mode. Check your notifications. If it actually went back into full power, you have a notification for that process. If there is no such notification, then it did not go back into full power and modules never turned back on after you defended the timer.