InsaneNutter
Resident Nutter
Updated to XeBuild GUI 2.091 which builds the 16537 Nand

You can go to 17150 following this tutorial, XeBuild should remap your bad blocks perfectly fine. I would however dump your nand from Xell and use that as the source nand.

New update to xeBuild GUI came out not too long ago.
Updated with an unofficial build of XeBuild GUI 2.098, which builds a 17526 Nand
Download:
XeBuild GUI 2.098 Download - Builds 17526 Nand
Updated with an unofficial build of XeBuild GUI 2.098, which builds a 17559 Nand
Download:
XeBuild GUI 2.098 Download - Builds 17559 Nand
If the 360 is banned and you have changed the keyvault when updating (or used a different keyvault in the past to what you have now) that can cause a profile to corrupt.
You can look at this guide here to try uncorrupt the profile: How to Uncorrupt a Gamertag or Gamesave from a Banned Xbox 360