Q: Troubleshooting for 30 inch Apple monitor

Apple 30 inch High Resolution Monitor

Mac Pro

10.8.2 OS

I turned on the monitor as usual i.e. pressed the switch lightly on the right lower side.  it came on VERY briefly and then went out.

Checked all the connections copious times, rebooted, etc. etc.

Checked out the computer on another monitor and the computer is working fine, but not the 30 inch monitor.

Any suggestions for trouble shooting the monitor.?

Thanks in advance,

Judy