it will not boot if you wont write original nand back...
first from 2 dumps of nand your j-runner must say they are identical, that means during reading all went well...
after that you have to make correct RGH2 version modified nand image. and again write it correctly
to make a correct RGH2 image you have to write ECC and boot to xell and get CPU key... only after getting CPU key you are able to make correct RGH2 image...
1.read nand twice
2.if both nands are the same create ECC (RGH2 must be selected in j-runner)
3. write ECC (press WRITE ECC button) if it says incorrect version check wiring.
/hook up cool runner, remove nand-x, j-programmer/
4. boot to xell and get CPU key by pressing get CPU key if you have console on network or just typing the key in j-runner.
5. after getting the key press create xebuild image (again RGH2 must be selected and correct dashboard version). write the xebuild image.
6. enjoy
so if it will not boot, write back original nand.
e79 means bad nand image. it happens.
first of... wich tutorial are you using. are you even using any? or just making up by yourself first time?