Thank you God, for excellent tech support we do not deserve who do their jobs far past normal operating hours. Amen.
Turns out it was an issue with the power cable, and one that was easily fixed.
Ugh, I really needed this break, man.
YOU GUYS. Thank you for being so freaking supportive through this stupid thing. Some of you even upped your dang pledges just in case I needed to buy a new piece of expensive hardware, one of you offered to lend me your Cintiq - I can't tell you how much all of these gestures mean to me. You took a really awful, frustrating situation and made it possible to get through. Thank you so, so much.
I'm going to make a cup of tea. What a weekend. Yeesh.