Instructions
Unplug everything that is connected to the console. This includes controllers, memory cards, video cables, power cables, Ethernet cables and any other accessories. Unplug the power supply from the wall outlet and the power cable from the power brick.
Plug everything back in with a solid connection and turn the console back on to see of the issue has been resolved. Turn off the console if you are getting the same error
Remove the hard drive by pressing the hard drive release button and pulling the device off the console.
Turn the console back on without the hard drive to see if that resolves the issue.
Request a repair service from Microsoft. If everything is properly connected and you are receiving an E74 error, then this denotes an internal hardware failure that can only be fixed by Microsoft. Click on the link in the Resources section to start your repair request. This issue is covered by your console's warranty for three years from the date of purchase.