you dont need the battery in to sort the sunroof drains out, its taking the A pillars off and having "lots of fun" in the acres of space behind them,,,,
wd40 might not be The best contact cleaner for the CEM, may pay you to get a dedicated one And give the connectors in the car a clean up as well, mechanical clean And solvent clean - good idea
yes a blocked sunroof drain = wet cem
you need to clear out the drains , esp the elbow and the ,(insert words here) end thats mostly blocked by design (ok its to stop wind noise but its too closed up ) theres a Few threads on here with photos on where/how for those,
if your that far from a dealer, you can get a dice/vida setup yourself, again there are a few threads on here,,
https://www.volvoforums.org.uk/showthread.php?t=253191 (i think) is one of the peeps with an offering