It appears the machine did in fact BOOT. It just didn't boot up Windows. It could be the old issues with old CD drives and failing hard drives but the clues and story are too slim. But I'd still swap those out.
Bob
My granddaughters computer. Has been working fine. Four days ago my wife took over a new modem {internet provider Clear}. Kids also connected to tv the same night.Computer will not boot up. Tried to do system repair and system response is CD drive is not available.When system gets close to booting {will not boot in safe mode] the fan starts racing I cleaned fan, heat sink and applied new thermal compound. The screen also goes very dim.
All four diagnostic lights are green
I am lost here. I have numerous Dell Optiplex parts here but I do not know where to start.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic