The C800/800+ Specification and Installation : Hot Swapping Power Supplies
  
Hot Swapping Power Supplies
You can replace a power supply while the cloud storage gateway is on.
To hot swap a power supply:
1 Remove the power supply as follows: Press the power supply's unlock lever downwards, while simultaneously pulling on the power supply's handle.
2 Install a new power supply as follows: Insert the power supply into the power supply slot, while simultaneously pressing the power supply's unlock lever downwards.