I had a 9500 with exactly these symptoms, and nothing that I did (or that the previous owner, an electronics tinkerer and unix geek extraordinaire, did before me) would make that machine get past being able to set the fans and disks a-whirring. I swapped ram, washed logic board, and fiddled with scsi until the wee small hours of several weekends. In frustration, I ended up acquiring another 9500 and cannibalizing the original for parts.I tried taking out the battery, reseating the CPU card and everything else again, waiting, pressing the red button, and still nothing. Pressing the power button starts the fans running, hard drive spinning, and the green LED on, and that's it.
I have given up for now.
At the time, I wanted a 9500 for an AppleShare IP server. Despite the "snappy" plastics, and the highly unintuitive case design, I rather liked the machine for being so wonderfully quiet. All of those machines, in my experience, were like that for some reason: the Quadra 800, 840av, the 8100, 8500 and 9500. The airflow must be good? I think relative silence one of the real must-haves in a machine.
My 9500 ran ASIP 6 for a goodly while. Now, having been replaced by an 8600/300 (with the side fan removed, which is unnecessary with the 604ev processor), the 9500 just sits and dozes.
Maybe I'll try my 2x604e 200MHz card in it with Debian 5, as it would not run stably in another (non-Kansas) 8600 in my possession. You never know ... maybe that 9500 would do the trick!