i have a dell dimension e310 that wont boot up. i have no beeps or sound just lights 1,2,3 are on steady. green power button is solid. The monitor has the Dell logo with Dell DVO51 Series BIOS Revision A04 is on my monitor when loading to start it up. I did blow it out, it was super dusty.  I also unplugged everything and plugged it back in. 

What do you think I should do with it? Or what is wrong with the computer itself?

i'm not handy with computer so i'm looking for any ideas or suggestions of what to do or try at this point.

Thank you for your help!