@dodo, dear friend!
Maybe something is wrong? Maybe you made a temporary, rather than permanent unlock your HDD? You must to disable HDD blocking function by MHDD - for all times, forever, before continuing to experiment with him.
Than... How you to do firmware reprogramming? All is correct?
Japanese's (J) and American's (N) MMCS firmware are interchangeable (except for J-01, of couse).
1. First, you must (or can) to fill in the disk image by
N-04 on your HDD (you already understand what you are doing and how, I hope!), after the all сontent HDD backuping, of course unconditionally. And I suppose, you know all about of all partitions on your HDD (what for what)!
2. Secondly, in the partition where is localized the loading.kwi file, in the root of this partition, you must replace this file by this
file. Old "ScreenData" in TFAT-partition - better to remove before.
3. Than, insert HDD in body MMCS and de-energized: throw off the car battery minus the terminal
by 15-20 minutes. After that, MMCS will perform a "cold" start with a full reboot of the operating system from main hard disk.
Sorry, for my english. And... sorry, for delayed response.