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Put your TRMNL in "boot mode"

Recover a device with malfunctioning firmware.

Ryan Kulp avatar
Written by Ryan Kulp
Updated today

For a TRMNL PCB to accept data transfer via a USB-C cable, it needs to be in "boot mode" or flashing mode.

Basic method

  1. Plug a USB-C cable into your TRMNL.

  2. Turn off the TRMNL.

  3. While pressing down on the circular ("boot") button below the power switch, turn the device back on.

  4. Let go of the boot button.

Stubborn method (if Basic does not work)

  1. Turn off the device.

  2. Hold down on the circular ("boot") button below the power switch.

  3. While pressing down, plug a USB-C cable into your TRMNL.

  4. Keep pressing the boot button and turn the device back on.

  5. Let go of the boot button.

If the above methods both fail, turn off your device for 10-15 minutes and try again. There may be a static charge or heat buildup that needs to dissipate.

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