Don't forget to plug in the Pro Trinket via a known-good USB cable to start the process. You should see the green power LED lit and the red bootloading LED pulse indicating that the Trinket is ready to start bootloading. If you've programmed the Pro Trinket since getting it, you can always get it back to the bootloader state by pressing the small onboard reset button | Don't forget to plug in the Pro Trinket via a known-good USB cable to start the process. You should see the green power LED lit and the red bootloading LED pulse indicating that the Trinket is ready to start bootloading. If you've programmed the Pro Trinket since getting it, you can always get it back to the bootloader state by pressing the small onboard reset button |