I found this on another website and it's supposed to work if you have the "3 Rings of Death 360".
360 that was flashing three red lights, which indicates an internal error.
If you have this problem try to fix it yourself before sending the unit in.
1) Remove your hard drive and/or memory units.
2) Run “Initial Setup” under the system blade.
3) Decline inserting HDD or memory unit when prompted.
4) Sync your controller and pop in a game.
Another solution:
"Initial Setup," in the System Blade.
The description explained that by selecting "Initial Setup," the console would run the system setup it executed the first time the Xbox 360 was used. With my HDD and memory unit detached, I knew my profile and saved game data were safe from deletion, so I went ahead with the procedure. The console did its thing and then prompted me to insert a HDD or memory unit. I declined. I was taken to the default Dashboard screen. I picked up my wireless controller and attempted to sync it to the console. It works! I plugged in my iPod and scrolled over to the Media blade. Yes!
I shut the 360 down, reattached the HDD, and turned the console back on (using the controller). This time, everything really was all good.
360 that was flashing three red lights, which indicates an internal error.
If you have this problem try to fix it yourself before sending the unit in.
1) Remove your hard drive and/or memory units.
2) Run “Initial Setup” under the system blade.
3) Decline inserting HDD or memory unit when prompted.
4) Sync your controller and pop in a game.
Another solution:
"Initial Setup," in the System Blade.
The description explained that by selecting "Initial Setup," the console would run the system setup it executed the first time the Xbox 360 was used. With my HDD and memory unit detached, I knew my profile and saved game data were safe from deletion, so I went ahead with the procedure. The console did its thing and then prompted me to insert a HDD or memory unit. I declined. I was taken to the default Dashboard screen. I picked up my wireless controller and attempted to sync it to the console. It works! I plugged in my iPod and scrolled over to the Media blade. Yes!
I shut the 360 down, reattached the HDD, and turned the console back on (using the controller). This time, everything really was all good.