search on the internet for "Dell amber LED" or something similar.
Here is one "how to fix it"
http://www.instructables.com/id/Fix-the-Dell-OLOD-Orange-Light-Of-Death/
I had a Dell that sat for a while and when I tried to start nothing but some light like you state (don't recall yellow, green, blue, red, pink or what color). It ended up the power supply for that computer was dead - I could have replaced the power supply for not too much $ but the computer was not worth any more money into it.
I had another old desktop that would start.
Took the hard drive out (of the broken computer) and set it up as a "slave drive" by moving some little jumpers and then connecting it into the working computer. I think this drive ended up being drive D or E or F...
Took all of the data off of the "slave drive" and put it onto a CD or DVD disk (the working computer had that drive) but I guess now it would be easy to use a large USB drive and move it in steps to the computer where you want it.
Recycled the old computer - kept the drive "just in case I ever need one"