Hi Niffy,
It doesn't work for me

While following your instruction, I used 2 files: update_jailbreak_
k2_install.bin and update_reginfo_0.1_
k2_2.5_install.bin. Is it right?
However, when I press Menu in Setting, "Update your Kindle" submenu is inactive. So, I cannot use it. I press restart instead. Is it ok?
while Kindle restarting, it told me that It was installing the file. However, it wasn't successful both step 2 and 5 so my Kindle is not registered yet. Could you please give me the solution for this?
My kindle firmware is 2.5.4.
Thank you so much for your response.