I admit I "solved" it by simply restarting the sim again. So whatever the problem is/was, we know this 'might' happen. MSFS is on 188.8.131.52 btw, which is the current version.
By default I start the CRJ cold&dark. Connected electricity as normal, but all cockpit displays stay black and dead. Only illuminated pushbuttons are normal. Am I really the only one? Regardless which aircraft state I load from the EFB, issue remains. All was good until I installed the 184.108.40.206 update with the ASUpdater today....