'New' PB 3400c won't boot up

I just picked up this used PowerBook 3400c for a song; it was said to have OS8.1 installed on its 2GB hard drive and 48MB of RAM.

I plugged it in to the AC outlet and pushed the startup button; got a chime and an illuminated screen, and I even heard the HD whirring around - but that's it. No little smiley Mac (do they still have those? Last Mac I used was an SE, in 1991, running System 6), no Finder, no icons, no nothing.

If in fact it has a working HD and a healthy OS 8 image, then what startup step have I missed?