iRiver H320 - 'Check HDD Connection'

[TheGimp]

Hi folks,

I've had this player for a good few years now.
Came on here when the original HDD died, and got the Rockbox firmware and a 4GB CF card, and had it working.
Then I started properly with smartphones, and this got relegated to a drawer.
Just now got it out again, but now:
- When starting the player, Rockbox V5 boot messages appear, terminating with:
Loading firmware
Result: -1
- Plugging into a charger first starts up the original iRiver charging screen, and starting it from there loads the original iRiver firmware (1.28 E).
- Shows 'Check HDD Connection' then 'Check HDD', and shows no files.
- When connected to a PC, the PC can see the files on the card, so it's connected and functional.
- I've removed the card from the player, connected it to a PC, and repartitioned, reformatted (FAT32) and made active with Diskpart.

Does anyone know what I can try next?

Also to note, I can start the player in 'Bootloader USB mode'. 

Cheers,
Stuart