G5 dual 1.8: dark screen, won't boot from CD, fan runs loud

My dual 1.8 G5 froze while working on a file.
Shut it down.
Now when I start it up, I hear it begin to boot (I can hear the hard
drive begin to read), then nothing. No ring and the monitor stays
black.
After a few minutes, the fans begin to blow very hard.

It won't boot from the CD. (But I guess if it's the video card, I
can't see it booting).

Any tips?

Thanks,
Lex