I've now managed to get ADB to reboot the tablet (ADB REBOOT BOOTLOADER), but running the next command (after the reboot while it's on the "Scroll by Storage Options screen") just hangs saying "Waiting for Device". The command being attempted is:
fastboot-windows.exe flash recovery recovery-clockwork-scroll.img
At this stage the tablet is not listed in Device Manager (although it is when I issue the reboot command).
Is there anything else that I can try using ADB to restore the tablet??