How to perform a factory reset
Short answer
Remove Major IV from your device and push and hold the control knob for 12 seconds. Release the knob when the LED turns purple.
If your headphones become erratic or unresponsive, follow these instructions:
Push and hold the control knob for 10 seconds to restart the headphones. If the issue persists, continue to the next step.
Plug your headphones into a power source using a USB-C cable.
Remove the Major IV and Major IV [LE], if present, from your audio device’s Bluetooth list and the Marshall Bluetooth app.
Push and hold the control knob for 12 seconds. The LED will change from white to blinking dark blue, then to purple. Release the knob when the LED turns purple.
The headphones have returned to their factory settings and are ready to be paired with an audio device.
Note: This will delete all user settings and the headphones will need to be paired again.