Yealink W52P User Manual page 31

Before connecting a cable, connect the grounding cable of the device first.

Do not disconnect the grounding cable until you have disconnected all other
cables.
Cleaning Requirements
Before cleaning the device, stop using it and disconnect it from the power

supply.
Use a piece of soft, dry and anti-static cloth to clean the device.

Keep the power plug clean and dry. Using a dirty or wet power plug may

lead to electric shock or other per
Regulatory Notices
23