to avoid resetting the config by accident this funcion of the button may have been disabled
NB! some network devices have different reset function depending on use of the button
- short -> reset (reboot)
- mediun -> reset to factory config
- long -> erase files system completely => also the boot image may be erased
-> connect a serial console to the console port of the switch and check console output
read this post: reset the 3750 to factory default - Cisco Community
hold the "mode" reset button up to 15 seconds or more till only one system green light.
Then release it, the green light will blink
Catalyst 3750-X and 3560-X Hardware Installation Guide - Troubleshooting [Cisco Catalyst 3750-X Series Switches] - Cisco
this is possibly also valid for the 3750 (without -X)
To reset the switch:
1. Press and hold the Mode button (Figure 1-2).
The switch LEDs begin blinking after about 2 seconds. If the LEDs above the mode button turn solid green, you can release the Mode button and run Express Setup to configure the switch. If the LEDs do not turn solid green, continue with the next step.
2. Continue holding down the Mode button. The LEDs stop blinking after an additional 8 seconds, and then the switch reboots.
The switch now behaves like an unconfigured switch. You can configure the switch by using Express Setup as described in the switch getting started guide on Cisco.com.
You can also configure the switch by using the CLI setup procedure. See "Configuring the Switch with the CLI-Based Setup Program."
