the error with the bootmii restore is a common one and easily fixed:
simply put the files (keys.bin and nand.bin) in root of the SD card, then:
1) Start -> Run -> cmd
2) Find the drive letter of your SD card, for example, F:.
3) Type this, replace the X with the drive letter: cd X:\
4) Type this: copy /b nand.bin + keys.bin nand.bin
5) Restore your new nand.