[Sir68k]

Thanks! The main problem I had was conflicts with the 'patch' peripheral during the erase/write. This peripheral allows for a small virtual overlay in memory space. It was used in previous devices to fix small bugs by overwriting a couple of words in the ROM. As all the flashing code needs to live in SRAM during flashing, the vector table needs to be patched to point to the code in SRAM. During the erase/write cycle you need to poll the values on certain addresses to figure out success - and if you haven't correctly disabled the patch overlay that can go wrong. That was how I got my first brick :)

[Xmd5a]

Thanks! Does it mean I can now upload tracks to the mz-rh1 without using their ugly piece of software? Or is this still impossible due to the use of cryptographic keys?

[Sir68k]

The firmware in a sense does not change anything regarding connectivity (for now). If you want to record normal MD, just use Web MiniDisc Pro. For HiMD, I recommend the Electron version of Web MiniDisc Pro, but it's not yet as stable as SonicStage (due to the complixity of Sony's system).