Troubleshooting; Keyboard And Mouse Are Not Working - Logitech MK520 Getting Started Manual

Troubleshooting

Keyboard and mouse are not working
Check the USB connection. Also, try changing USB ports.
Move closer? Try moving the keyboard and mouse closer to
the Unifying receiver, or plug the Unifying receiver into the receiver
extender cable to bring it closer to the keyboard and mouse.
Check battery installation. Also check the battery power of each device.
(See Battery management for more information.)
On the mouse bottom, slide the On/Off switch right to turn on
the mouse. The Battery LED on the mouse top case should light green
for 10 seconds. (See Battery management for more information.)
Logitech Wireless Combo MK520
®
Mouse bottom
On/Off switch
English 15