Great, this worked.
Here's what I did:
Press hold down volume button and press top power on button.
After boot into Sansa firmware connect Clip Zip to PC.
Sansa would not mount; select Settings > System Settings > USB Mode > MSC; reconnect Sansa; successful mount.
Settings > System Settings > Format > Internal Memory; successfully formatted.
Reconnect Sansa to PC; install Rockbox bootloader and firmware, etc.
Happy, happy Clip Zip.
Thanks for saving my Clip Zip.
Cheers