If your BURST Toothbrush is not turning on the First step with the brush or flosser is to try a reset on your BURST Flosser or Brush. This is done by plugging the unit in to charge, Once charging go ahead and hold down the power button, After a couple of seconds all of the lights will illuminate on the unit. You can then release and the lights will go off after a second and the unit will then start charging. Let it finish the charge and use the unit as normal.
If this reset has not resolved the issue then take a quick 5-10 second video of the issue you are having and submit your warranty claim through the BURST website here: https://www.burstoralcare.com/register
Here is a video on How to reset your BURST brush if you need it: