4400/200 won't turn on?

I have a PowerMacintosh 4400/200.  I pulled it out of storage to try to
run something on it, and...I can't make it turn on.

The power cord is live; I'm sure of this not only because it ought to
be (plugged into a lit powerbar) but also because, as I plug it in, I
can hear the tiny little tick as standby power powers up.

But pressing the front-panel power-on button does nothing, nothing at
all, as far as I can tell.  In case the switch was dead, I pulled the
connector off the pins on the board and tried shorting them with a
screwdriver.  Still nothing.

This is with nothing at all connected except the power cord.  I do have
a DA-15 with two pins jumpered to fake out the monitor detect circuitry
on mac68k machines; I tried connecting that to the monitor DA-15 and it
made no difference as far as I could tell.

I looked over the wiring and there's nothing obviously disconnected,
except the back-panel SCSI cable (which I have nothing connected to on
the back panel, so it shouldn't matter).  In particular, the main power
connectors and the small soft-power control connector next to it are
indeed connected.

Any suggestions for another place to look, or is this machine probably
just a lost cause?

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