Well here in England I am pretty sure that modding consoles is not legal, there have been a number of court cases on it and I think the Conglomerate Nazi's won out........
I am sure you are already a member of one somewhere but there are a few X Box modding forums out there - a Google search might turn one up for you.
Our help is done here really, you managed to burn a disc in the end altho I don't think the RiDisc DL's will help your cause much (repeat after me, Verbatim DVD+R DL's only, Verbatim DVD+R DL's only, Verbatim DVD+R DL's only...) so the problem with the playback of your game cannot be looked at here.
Good luck with the Google Search...