Apple iMac G5, 20-inch - Manual (Page 247)

iMac G5, 20-inch Troubleshooting - 23 Diagnostic LEDs
5. As you hold the metal foot, tilt the back cover up and lift it away from the computer.
The back cover with the foot attached should come off easily. If it doesn't, make sure
the screws are turned completely counter-clockwise, but not too far.
6. To protect the computer from electrostatic discharge, ground yourself by touching a
metal surface inside the computer. Warning: Always discharge static electricity
before you touch any parts or install any components inside the computer. Don't walk
around the room in socks or bare feet, for example, until after you've finished these
steps.