How to judge whether is hardware failures in the printer?

The steps to print a Self-test page are as follows:

1. Disconnect the USB connection and load paper.
2. Wait for the green light to turn on (if there is no green light, please do the automatic label identification), press the feeder (green/red light) button three in a row, and release it. After you wil hear three consecutive beeps.
3. It will print out the self-check label. If you can't print a self-test page, don't hesitate to contact us.

If it can't to print a self-test page, please contact us.