I had the RROD (three red LEDs) a couple of days ago, and after a few attempts to reboot without results, I took a look at the secondary error code, which turned out to be 0020. I then took the thing apart and applied llamma's X-clamp replacement and decided to add thermal paste, since M$ apparently hadn't when the console was assembled.
Now, when I turn it on, it boots to the dash without problems, but the front panel led's don't work, nor does any wireless controller connect, and the CPU gets real hot real fast, causing the fans to go into overdrive.
I guess this could be a possible short between the CPU and the front panel?