How do you remove a Dell Optiplex GX270 small form factor motherboard from its case?

My GX270 SFF motherboard is dead. I need to know how to remove it from its case before I buy a replacement. I unscrewed the only screw that I saw that seemed to hold the motherboard directly to the tray, and the four screws for the CPU retainer, and the motherboard still would not come out. Something seemed to be holding it from underneath. How do I work underneath it?

Maybe it's like the 110:

http://support.dell.com/support/edoc...emboardremoval

There are several other steps - other things you have to take out or disconnect first, some of which you must have already performed, others probably not. They're all outlined in the above document which begins at the top of the page.

See also (Optiplex GX270 small form factor specific, but less well organized):

http://support.dell.com/support/edoc...n/ug/index.htm

and it's related pages:

http://support.dell.com/support/edoc...M/EN/index.htm

http://support.dell.com/support/edoc...EN/replbrd.htm