Elecom M-XGS31BBSK Series User Manual page 9

The LED will light up white when the connected device is "PC1" and green
when "PC2" is connected.
When paired with only one device on either "PC1" or "PC2", the existing connection will
be lost when you switch to the unpaired side.
Switching back to the side paired with a connected device will restore the connection.
Connecting and setting up the mouse
Windows®
1.
Turn the power ON
1) Remove the battery cover.
2) Remove the battery insulating tab.
3) Put the battery cover back on.