Boot Issue - Compaq Presario 4540

Hello All,

I am hoping that someone out there has experienced the following
problem. I maintain a handfull of Compaq Presario 4540's at my place
of employment. I've had 2 of them completely crap out on me in the
same way. They will not boot at all, even to a floppy. Additionally,
you cannot access the setup configuration (CMOS settings)... It
appears that the on-board video is not working, as there is no display
what-so-ever. The monitor light never turns green. When they are
powered on, the CD-ROM and hard drive are temporarily accessed, but
that is the end of it. I've tried removing cards (modem, NIC, etc...)
to narrow down the possibilities. Also, I've tried a known-good video
card. No luck, however. Thank you, in advance, for any commentary on
this annoying problem!