The drive in my LS-GL failed. I have replaced the drive and followed the tftp boot instructions.
The unit boots via TFTP and the firmware updater finds it, I entered debug mode and selected rebuild partition table as this is a new disk.
However when I try and run this I get the "Format required, delete all data" warning. I confirm this and then the format will fail about halfway through with ACP_STATE_FAILURE (I know about the issues that cause this during the firmware update, but this is happening at the format stage). about 5 minutes later the unit will start bleeping with only the errror light flashing. At this point I need to repeat the tftp boot to talk to it again.
Ignore my previous post.
I made a flawed assumption that a new disk would be ok, after checking it with smartmontools it appears to be faulty.
The replacement I obtained works fine and the format/firmware update process worked.