The Blinking '?' icon means that the Mac could not find a valid System folder on any of the attached bootable devices.
Is the Hard Disk spinning up at boot time? You may want to zap the NVRAM to reset the default boot device path. To do this, hold down command-option-P-R when the machine starts. You will hear the startup chime twice.
To do a more complete reset, you will have to open up the mac and either remove one of the memory modules, or pull out the NVRAM battery for a few minutes. You shouldn't have to do this except for rare cases.
If you still cannot boot into MacOS 9, your only choice is to find another boot volume, like a startup CD. When the computer boots, put the CD in and hold the 'c' key down. You should be able to boot directly from the CD, bringing you to the MacOS 9 desktop. When your internal drive mounts, take a quick look to see that everything is in place. Run Disk First Aid to scan for any potential problems. Afterwards, just to be safe, do a clean install of MacOS 9. Its not as painful as it sounds, you just need to spend some time moving extensions, control panels, and preference files over afterwards.
If the disk does not mount, you have a more serious problem. Apple does not package any tools that are really capable of resurrecting dead drives that won't mount, so you will have to invest in something more robust in this rare situation. Norton Utilities 7 has saved my arse in such a case.
It was lucky I had my PC otherwise I would have been stuck for my job.
