Well, I flashed with the 6000 version of the OZ 3.5.3 release (opie updater.data if that matters). I followed the instructions on the Installation site exactly. It went through the flashing process and gave me the "Please reset" message.
I waited a couple minutes to make sure it finished, then hit the reset on the back with the stylus, then tried turning it on, but nothing happened. I repeatedly tried to reset, power-on, no results. I opened it up and turned the battery backup off, left it for a while, put it back together and returned it to the base; it started charging. I left it for over an hour then tried to boot again, no luck.
I kept it on the charging base all the time except for when I had to physically remove it to remove the battery.
I'm not sure what else to do..