Can't get into DFU mode

[mit420]

hi
i was trying to jailbreak my cousin's ipod touch 2g 8gb which is a MC model
it was on 3.1.3 and i restored it to 4.1 and worked fine and now when i try to use redsnOw or greenpoison to jailbreak it i can't get it into DFU mode i tried so many times.
and worse i can't even downgrade it to 3.1.3 again because it gives me an error
can somebody help me?
please don't tell me how to get into DFU mode by pressing the power and home button because i've done all the possible ways that are out there.

thanks in advance

[Cowboy]

Try ireb