The best ‘bug’ I have ever seen…
Way back in October 2013 Cisco slipped out this little field notice to customers and engineers across the globe. The position and function of the mode switch is such that it can be pressed by the protective boot on certain types of cables and cause a reset to factory settings.
Certain types of snagless Ethernet cables have protective boots that extend too far forward and above the plastic latching tab. When this type of cable is installed in Port 1 of any 48-port model of the Cisco Catalyst C3650 or C3850 Series switches, the boot might press and hold the Mode button, which invokes Express Setup and reboots the system.