Xbox 360 no picture

NEVER EVER!!! do the towel trick. NEVER PERIOD! It may work for a little while, but you are doing waaaaay more damage than good. The xclamp fix is the only way to rectify this. If you send it microsoft, thats what they're going to do, reball the gpu and cpu and put new, just as shitty, xclamps on it. Then, a couple months down the line, the same thing will happen. The xclamp fix is backed by engineers and is a permanent fix to over 90% of xbox problems. Here's why...

The xclamps microsoft uses are design flaws, they are all designed to fail. As the gpu and cpu heat and cool consistently, everytime the console is ran and turned off, the xclamps warp. The warping x clamps cause the heat sinks to raise from their respective gpu or cpu (most commonly the gpu, the short heat sink). At the same time, the solder balls beneath the gpu and cpu melt and re harden away from the mother board, causing the rrods. The xclamps have no way of dealing with this. Installing bolts fitted with lock washers on the bottom, nylon against the motherboard and stainless steal against the heat sinks works 95% of the time.

Here is my recommendation
If the xbox is still under warranty (I mean no one has broken the sticker) don't open it yet
The reason for this is microsoft will warranty an xbox 360 against the three RROD
The problem you are having is/maybe related to the same thing and what is happening is the graphics processor is no longer responding properly.
Many others on this site have recommended a fix that I am hesistant to recommend, but does work, TEMPORARILY.
I only recommend this fix if you are trying to preserve the console s warranty as this is a non invasive fix.
All you need to do is wrap the console up ina thick blanket or several towels (do not use wet towels as water damage is not covered under warranty) and turn the console on.
This will cause it to super heat and eventually overheat
(this is not particularly good for the console, or permanent)
Once it has overheated (about 45 minutes in the towels/blanket)
unwrap it and let it cool.
After about 1 hour of cooling try to restart the console and see if you have video
For an out of warranty more permanent fix try the xclamp replacement mods outlined in other sections of this forum or search on google for xclamp replacement