WARNING THIS MAY NOT WORK FOR YOURS. IF ANYTHING GOES WRONG IT IS MOT MY FAULT.
Make sure the disk is not the problem. If there is scratches, there may be nothing wrong with the Xbox
Try another disc and see if the same thing happens
Try to open and shut until working (or 5 times max)
If that doesn't work then tip it to the side so any dust falls down
If your disc compartment is misaligned, you may need to lightly press down on the Xbox logo, or near the button to open it. If it won't open hit the top but not too hard