Instructions
Four Lights
Check that your AV cable is properly connected to your Xbox 360. Four red lights indicates a problem with the AV cable or connection.
Turn off your Xbox 360 and disconnect and reconnect your AV cable.
Wipe the metal area of the AV pack with a dry cloth, if disconnecting and reconnecting does not solve the issue.
Swap the AV cable with a fresh cable if none of the previous steps work.
Two Lights
Turn off your Xbox 360 system. These lights (top and bottom left) indicate that the system has overheated.
Do not turn on or play your system for several hours.
Contact Microsoft Support if your Xbox 360 still displays these red lights after cooling off.
Three Lights
Check the power supply brick on your Xbox 360 when three lights appear red. This indicates an issue with the power supply or a general hardware error. Look for a small light on one end. It will glow either red or green.
Disconnect and reconnect the power supply cables from your Xbox 360 and the power outlet. Reconnect the cord to the video game system and then to the outlet. Check if the light on the power brick remains green, remains red or changes from red to green after reconnecting the cords.
Plug your Xbox 360 into an outlet in another room if your light remains red after reconnecting the cables. If your Xbox 360 works in a different room, there may be a problem with the original outlet or power strip (if you were using one).
Disconnect the power supply from both the wall and your Xbox 360 if the red light still appears on the supply brick. Allow the power supply to cool for at least 30 minutes in a well ventilated space.
Turn on your Xbox 360 to check the status of the red lights. Contact Xbox support if the light on your power supply remains green but there are three red lights on the front of your Xbox. You can also contact Xbox support If your power supply remains red or unlit after these troubleshooting steps.
One Light
Refer to the error code on your screen when the bottom, right light on your XBox 360 appears red. This light indicates a specific hardware error.
One of the more common errors is the "E74" error, which will cause graphics issues on your screen. Microsoft now covers this error in its warranties.
XBox-Experts describes other possible error codes including:
"E640" - Bad DVD flash/ dead flash chip (Timeout)
Contact Microsoft and alert the customer service representative of the error code on your screen.
Follow any instructions to troubleshoot the system or send it in for repairs or replacement.
"E65" - Bad DVD flash/ dead flash chip (DMA)
"E66" - Wrong DVD-drive version
"E67" - Broken harddrive (Timeout)
"E68" - Broken harddrive (DMA)
"E69" - Broken harddrive (HDDSS)
"E70" - HDD rrror filesystem/not found
"E71" - Dashboard update error (NAND related)
"E72" - NAND issue (loose pin/ bad flash)
"E73" - Cold solderjoint (Ethernet/Southbridge)
"E75" - Network chip cold joint/ wrong vendor
"E77" - Dead network chip
"E78" - AsicId check failed
"E79" - Broken harddrive (Xam.xex)
"E80" - NAND - Wrong LDV version