I found the culprit! I had the screw securing the corner power supply board too tight, which caused the body of inductor L101 to contact pin #3 on the LCD board. Backing off on this screw just a little bit yielded enough clearance to put things right! Next time I remove the entire unit from the case, I'll flatten the solder hill on pin#3 and/or put a bit of kapton tape between L101 and pin#3. Unfortunately, I misplaced my kapton tape a couple weeks before my QMX build, but until then all seems good.
