The backup battery in my Q700 died recently. I thought people
might like to know the symptoms: the machine won't boot at all.
It doesn't find its SCSI devices and immediately spits out any
floppy inserted without reading anything from it. It just sits
there with the flashing question mark in the floppy displayed.
  The battery in the Q700 is a 1/2 size AA battery, available
from Radio Shack for $10. It is under the floppy/HD assembly,
which you have to pull out the power supply to get to.
  When I pulled the old lithium battery it still read 3.6 volts
(it is nominally 3.5) but I believe it could no longer source
any significant current at that voltage. With a fresh battery
the machine is good as new.

--Denny