Unmodding Xbox 360

I own an Xbox 360 Elite (Modded).
Just moments ago, I inserted a pirated FIFA 12 disc into the drive. Like some games previously, the dashboard needed to be updated first in order to proceed. I clicked yes, and so it started updating and the update stopped halfway (Error: 3151-351F-B800-0F00-C000-0013).
I've looked it up online, and it seems like I'm not the only one with this issue. Basically, I'm stuck at that screen, despite restarting my console.

Thing is, right now, I am considering getting it back to the unmodded condition. Is that possible? I'm not here to discuss modding my console yo, I wanna do what's right!

I'm just tired of living in fear, I've never played online yet and I would really love to do so. But, original games are expensive, I guess I'll have to save up then.

So, my questions are:
1. Is it possible for me to fix my Xbox on my own? If yes, how do I do it?
2. How much do original games usually cost? (Wasn't really bothered up till now ) And where can i get cheap games?
3. How do i play online? (Sorry, I've never played any games online before )

Anything else I should know about using an unmodded console?
I'm in a dilemma now. As i do wanna play online.
Any advise?

Please don't flame me guys

Thank you very much.

ur drive is mod with LT , so just flash back to stock,
fifa 12 NEED dash update. dont update using disc.
get the update from internet to USB and update.
DO NOT however dload latest dash, since it is not tested.
13599 should be good.

1- just flash to stock fw to get original back
2- depends , some o it even the price of bluray ps3 game tho its dvd.
3- u need ORI and xbox live account, which also need to pay

- u cant u pdate dash using pirate disc. u will face many uopdate problems.
use USB stick/pendrive

So it.s posibble to unmodded xbox? I heard if the xbox just been softmodded then we can unmodded for online play purposed issit true? Im keen to play online though.

u can just flash back ur drive to stock fiw. to unmod it.
playing mod machine online is not recomended.
it could get ur machine banned and not xlive able anymore/

u can get an stuffs like wasabi360. that can get u running
Ori and isos at the same time.