I'v already disconnected my nandflasher from my xbox. If there someway I can change the nandflash.bin file to include the bad block rewrites, that way I can put it on a usb stick and flash with rawflash on xell?
rawflash isn't going to touch either of these blocks, no matter what you do to the image you feed it. Technically it's the safest way to treat such blocks at a raw level, even though it occasionally produces results like yours. Hence why it's called rawflash, and not doeverythingforyouflash

block 0xb2 seems bad (204)
block 0x2a2 seems bad (250)
the problem is, 0xb2 is likely not bad (yet) and just has a single bit error which is correctable by the controller. In your dump you are getting the corrected data, and because of that the block doesn't seem to have any issues when you examine it with tools like flash tool because the bit error doesn't exist in the dumped data.
Block 0xb2 likely is already labeled by LBA as 0xb2 and unless you can overwrite it with 0x0 data after you remap it, the system will keep trying to use it as 0xb2 even though it has old data in it resulting in essentially a corrupt file in the flash - in this case, dash.xex which produces E71.
Here are two variations of rawflash,
not meant for normal use but only to overcome problems like this... remap your block with the ecc error to the end of NAND as mentioned above, zerofill the origin block, and try the no_ecc_care one first. Once it works, do not use these "no care" versions again, they won't be needed unless a new issue comes up later.
Another option to manually remapping, is to simply get out a hex editor and write 00 in the byte at (0xb2*0x4200)+0x205 (=0x2DE605, it should be 0xFF with 00 on each side of it) in nanddump.bin that you are feeding to your image builder. This effectively marks the block as bad, and the builder should remap it for you.
This version simply ignores ecc errors, and should be able to correct your issue with 0xb2 if you remap it as described:
rawflash_v4_no_ecc_care.zip @
http://www.mediafire.com/?1b81mqwraoscgrlThis version just puts onscreen message when ecc error or bad block error are detected, but otherwise attempts to read/write the block anyway:
rawflash_v4_no_badb_care.zip @
http://www.mediafire.com/?twsmlgdpmre8su4Now the lecture on why you shouldn't use these normally: when you tamper with blocks that are marked as bad, you may have no way of marking them as bad again. Good luck!