I decided to start over with a plain Debian install after wrestling with Solaris x86 and taking a break from coding at home. I hit the power button, which flashed briefly and then ... nothing, shut down. Reseated the PSU, and again no joy. Checked for bent pins or something dumb like a loose plug and all seemed fine.
The Z800 power supply has a BIST (Built-In Self Test) feature and can be pulled out easily, so I just yanked it out and plugged it in to check to see if the green BIST lamp went on. I did not even have to look: it kept sputtering, the fans starting to spin and then stopping, over and over. Diagnosis: dead PSU.
My laptop and my daughter's laptops also started glitching this weekend: mine would not stay on unless plugged in despite a new battery, and my daughter's laptop could not find its hard drive after a reboot. Both will have to go to the shop tomorrow.
And that, despite various annoyances and being a bit out of date, is why I like the Z800. The interior is clean; every part can be pulled out or even hot-swapped; it has a nicely detailed PDF manual freely available online; and while I have never been that good at hardware I at least know my way around the interior of a PC and can recognize all the parts and do basic replacements.
The MacBook Airs on the other hand are sealed shut with memory soldered in place, and there is not much else I can do than just haul them to Grand Central and drop them off at the Apple Store.