As usual, equill, your advice was spot-on. However, after I left it plugged in for a day or so, I tried to press the keyboard power key, and it still just sat there. Slightly dismayed, I was about to give up for now and put it in storage (I don't have too much longer at home here). But, I decided first to try to jump-start it (remembering the antics of battery-dependent machines like the LC 475), so I quickly cycled the mains switch before pressing the keyboard button, and I got the [happy startup noise]! Yay!

I wouldn't have thought of leaving the thing plugged in for a day. Now I can load an OS on the thing before I put it in storage.