Check that the computer is plugged into a power source and that it is turned on.
Check that the power indicator on the front panel of the computer indicates that
the power is on.

Check that the battery packs are inserted properly and that they are charged.

Make sure there is no diskette in the floppy disk drive.

Confirm that the power cord and all cables are connected firmly.

If you have plugged the computer into an UPS, make sure the UPS is turned on
and working.

When you reconnect devices (other
than USB devices), be sure to turn
off the computer as described in
"Shutting down your computer".
If you turn off the computer in
other ways, it may result in data
loss.