The reason I think it's software is that these computer units never really power off and often, initializing the USB interface will allow low level functions, such as the software flash function, to run without any apparent activity from the display, etc. Non computer units will power down, same as when you pull the battery, but most of the computer units will have a very low power mode that they live in (sort of like sleeping) when you hit the power button or remove the batteries. There are likely coin batteries or capacitors that will allow this. Often, you can run the interface programs and perform diagnostics, software updates, etc while the unit appears to be shut down, hence my suggestion to try to reflash the software.
Since you've got it boxed up it's a moot point. I'm sure ML will take great care in providing you with a fast turn around and explanation of what was wrong as I have to assume they monitor these forums at least to some degree. They'd be foolish not to.
Keep us appraised of how this plays out. I'm toying with the idea of buying a second MD and the 3030 is number 1 on my list, but a few complaints like yours or reports of poor service would quickly cause me to reconsider that unit or any ML unit.
Thanks and best wishes for a speedy resolution.