Xbox. my sons xbox will not eject disk or open at all ? error message says call for service ,so i

Question

my sons xbox will not eject disk or open at all ? error message says call for service ,so i did they say to send in and pay 120.00? ya ok so i opened it up relized its a hard drive dvd main board etc, < basically a computer > it blinks red then green should i get a nother dvd from another xbox or is there a way into the hard drive ? what could be rong ?? thanks