You're not going to get much more support to be honest without using the correct tools! All speculation, could be a new laser needed for your drive, whoever flashed your firmware messed up, your old backup games should still work if they worked before. If I was to start anywhere it would be with whoever flashed your firmware and try someone else backup game. At least then you're starting to narrow things down.
Give us more info aswell, what errors are you getting during the burn.
Is everything passiing in abgx360's latest version, if the burn fails run it through abgx again to see if there is any more errors, are you using the latest version of imgburn.
Imgburn settings for burning, set the layer break to 'calculate optimal' burn speed to 2.4 or 4, dont use your computer while the burn is taking place.
How many drives have you in your pc, is it failing with the one drive the whole time or just one.
Do any of your old backups that used to work on older firmware still work now since you had it updates to lt3.0?
Get someone elses backup thats confirmed working on theirs and try it on yours. Are the originals playing on the xbox fine?
You have two problems, your old backups wont work and the new backups your burning wont burn, answer all those questions or im just going to ignore any further posts, its no use saying i got this and it wont work, details details details.
HTC Desire S~Tapatalk