From where did you buy it? If you charged it on a credit card, you can search your purchases and print out proof of purchase. It might also be a good idea to contact Fitbit Support and see what they say. But before that, you should try to restart your device. Press and hold the button on the left along with the bottom button on the right until then Fitbit logo appears. (About 10 seconds) You may want to try that a couple times. It might bring your Versa Lite back to life.
