A8m2n-la fans run no boot no beep no screen

Try all these steps:
http://www.tomshardware.com/forum/261145-31-read-postin...

Basic troubleshooting involves unplugging everything not needed to boot. All the cables to drives for example.

I was using the media center when the screen froze w/ light and dark blue diagonal lines...had to unplug it to shut down.Upon plugging it back in the fans operate and thats it. I took it to staples (where I bought it) and a week later they called and said to come pick it up because they won't touch a motherboard. HP tech said to unplug everything take out the ram (which requires removal of the hard drive)(not backed up!) and then plug it in and listen for a beep. I have not done this yet. Should I?

I didn't realize this was a HP computer. While trying to find this board as an Asus - they don't list it on their site - I ran across this old Tom's forum thread. It mentions a lot of people having good luck disconnecting the front panel USB and Media card readers. I recommend that before anything else.

Read this thread:
http://www.tomshardware.com/forum/248331-30-a8m2n-pavil...

If handled carefully, there's no problem removing any component inside your box. Just be careful and make lots of notes - don't count on your memory to remember what you did and how wires/cables connect. Note the position and direction of cables and label them as you go. Take anti-static precautions - likely don't need anything like a grounding strap, but self-ground yourself by touching the power supply while still plugged in then don't move around a lot! And then unplug the unit!