Attention Do not open your computer or attempt any repair before reading and understanding the "Important safety information" in the ThinkStation Safety and Warranty Guide that came with your computer. To obtain a copy of the ThinkStation Safety and Warranty Guide, go to Lenovo Support Website
This section provides instructions on how to remove the computer cover.
Turn off the computer and wait three to five minutes to let the computer cool before removing the computer cover.
To remove the computer cover, do the following:
Remove any media from the drives and turn off all attached devices and the computer.
Disconnect all power cords from electrical outlets.