42PG20D: xbox won't connect to tv invalid format

Hi there Jadekira86,

Thanks for reaching out here in Xbox Forums. I understand there is an issue with the Xbox Video resolution. I recommend trying a soft reset of the console this will help refresh the operating system and settings of the console. Check out this article:
Soft Factory Reset(while
keeping games and apps)

Before resetting your console make sure of the following:

• There is a stable network connection.
  
• The information for all profiles is known (email and passwords)
  
• If the console is not responding properly by providing the different menus. We are going to approach this differently.
  

Try this:

1. Power off your console, and then unplug the power cord to ensure that the console is completely powered off.
   
2. Wait 30 seconds, and then plug the power cord back in.
   
3. Press and hold the
   BINDbutton (located below the Xbox button on the console) and the
   EJECTbutton (located on the front of the console), and then press the
   Xboxbutton on the console.
   
4. Continue holding the
   BINDand
   EJECTbuttons for 10-15 seconds.
   
5. Listen for two “power-up” tones a couple of seconds apart. You can release the
   BINDand
   EJECTbuttons after the second power-up tone.
   
6. The console should power up and take you directly to the Xbox Startup Troubleshooter.
   
7. Select Reset this Xbox
   
8. Select Reset this Xbox and Keep Games and Apps
   

Give it a shot and let us know the results.

Fyi invalid format usually means a resolution problem

Resync your tv

Hey there Jan thanks for taking the time to bring this issue to us.

We apologize for the inconvenience this has caused but rest assured we are here to help, we have seen this in the past
and since the issue could be on the actual OS of the console so we would suggest a >Soft
Factory Reset<
(while keeping games and apps)
IF AND ONLY IF THE FOLLOWING CRITERIA IS MET:

• There is a stable network connection.
  
• The information for all profiles is known (email and passwords)
  

Once the setup is complete it will ask if we want to keep settings or manual setup
lets do manual setup.

If the dashboard cannot be accessed.

1. Unplug the network cable if you're using a wired network connection.
   
2. Power off your console, and then unplug the power cord to ensure that the console is completely powered off.
   
3. Wait 30 seconds.
   
4. Plug the power cord back in.
   
5. Continue holding the
   BINDand
   EJECTbuttons for 10-15 seconds.
   
6. Listen for two “power-up” tones a couple of seconds apart.
   

NoteIf you
don't hear two power-up tones after 15 seconds, it means this failed. Likewise, if you hear any “power-down” chirps, that also means this failed.

1. You can release the
   BINDand
   EJECTbuttons after the second power-up tone.
   

Once the troubleshooting screen comes up select reset this console (Keep games and apps)

Give it a shot and let us know of any changes!

This has happened to me as well. Tried getting hold of Bungie but they have a wonderful system in place to make it impossible to actually speak to anyone there. I'm stuck. If anyone out there has a solution I'd be very grateful if they could let me know?
(I tried the solution supplied by Kothos below but it didn't work for me. Thanks anyway, mate).

Fixed it! Turns out it was the 3D setting and I don't have a 3D TV. How it glitched itself into that setting I'll never know, I didn't do it.

But I logged in with an alternate account, memorised the stick and button moves to get to Settings and change the 3D option and it worked! Stupidest problem I have ever encountered in 18 years of working in IT.