Airsense 10 power supply odd behavior going from 120V to 240V and back

I have an Airsense 10 Autoset that I received from DME in January brand new - it showed zero hours on the motor.

Recently, I plugged it into an 120V 60Hz outlet in USA (where I live) after travelling to Europe and it wouldn't turn on - no green light on the 100-240V ResMed power supply. I tried plugging/unplugging in a few times and different outlets in different rooms to no avail. This was after using the same power supply successfully for over 2 weeks in Ireland & UK 240V 50Hz. Next day I tried it again and it worked, and has powered CPAP four nights in a row with no issues. Any clue why it initially did not work? Perhaps the power supply got into a weird state after using it on 240V for a couple weeks and going back to 120V? Its only 6-7 months old. Anyone ever experience something like this?

The power supply is a 'switch-mode' that takes either voltage... it does not remember the last voltage, it just works with what it gets.

I suspect a cable problem, like where the cord plugs into the brick. Cram it in there tightly!

I suspect that the plug in the adaptor is loose.