I have a phat Xbox 360 which was modded and was working perfectly fine. One day I decided to apply a system update to the Xbox from the website . I applied the update and followed the instructions but after the update when I put in a game to play, the dashboard gave me a "Play DVD" option so I thought that the system update had reflashed the xbox back to stock firmware. So I took it to a guy to get it flashed and he said he'll load LT+ 3.0 in it but first in order to check it, he put an original game (not a backup) into the X360 and he still got the "Play DVD" option. He then tried changing the drive but that didn't work either, so he told me that there is a problem with the motherboard (since original games are not working) and that the Xbox is useless now. He says he can get the motherboard changed but he does not guarantee success. What should I do?