Solution 1. Isolate all peripherals
“Xbox 360 error code E69” appears when your Xbox 360 diagnose a faulty peripheral is connected. It could be the display cable or a USB storage device. To isolate the peripherals, remove all peripheral that is connected to your Xbox 360 except the power cable. Power on the Xbox 360, then reconnect the peripheral one by one, until the power button led light turns red. The red light indicates that the newly connected peripheral is faulty and should be replaced. If all peripherals are reconnected and the led light is still green, it concluded that it is a loose peripheral connection.
Solution 2. Test your Hard disk drive (HDD)
If all peripherals were proven good, it is possible that the caused of “Xbox 360 error code E69” is your hard disk drive. Try to reconnect the hard disk drive it could also be a loose connection. If the reconnection was unsuccessful. Remove your hard disk drive to your Xbox 360 and test it using a computer.
Any defect found on your Xbox 360 hard disk drive, will result in a replacement to fix the problem. If proven defective, order a Hard disk drive to Xbox Online Service Center. If the test resulted good, your Xbox 360 HDD SATA cable might be faulty, try to buy a new one.