I am in a computers class right now, and one of my assignments was to get model and type of CPU off of my computer. I followed all of the steps when taking a computer apart. I put everything back together and now I turn my computer on and it powers up but the light stays orange, won't go to green. You can tell it is running tests because the lights on my CD and DVD drives both turn on.
If you could list the steps you took, it would be helpful.
The CD/DVD drives lighting up doesn't really mean anything.
If you were unplugging power connections there's a good chance you plugged something back in incorrectly. Go back over everything step by step to make sure it was done correctly the first time. If you are unsure of anything ask us, it can be confusing the first time you do this kind of thing.