Sound works fine but lost the video. Tried unit on another tv and same problem.

The no video problem is becoming a common one on the Xbox 360's.

First check to make sure your video input cable is set to the proper input. Look on the side of the connector that plugs into the xbox itself and you will see a switch with TV and HDTV labled above it.
Slide the switch to the position according to the type of tv you're using with your xbox.

You can also try holding in the right trigger and pressing the Y button as soon as you turn on your xbox. The easiest way to do this is to turn the xbox on using the controller.

If these solutions do not work, you "may" have a bad video cable.

You can open a support case with Microsoft to have your console repaired. If it's under warranty, Microsoft will repair it for free.

If not it will cost you either $99 (open online support case yourself at www.xbox.com) or $120.00 (call xbox support at 1 800 4my xbox)

The last option is to repair it yourself if you think it's within your capabilities.

There are numerous articles on the internet on how to repair various problems with the xbox. Be aware the available solutions may or may not apply to your individual situation.

One of my 360's had the same problem a couple of weeks ago. I decided to fix it myself instead of paying Microsoft but I had nothing to lose as my warranty had expired and I had another console I could use regardless.

Get new AV cables for the xbox and if that doesnt work, send it off for repairs. That is most likely the problem though. Microsoft will charge $100 to do the same thing i just told you to do.