Hello, although X728 can be used together with X715, but it needs to be reminded that if it is not operated properly, it may cause damage. When X728 and X715 are used together, it can only be powered by 2PIN line, not by GPIO. If possible, please provide your order number. If possible, you can provide some pictures (about your question), preferably a video, and send it to our email. Please contact us at support@geekworm.com. We will try our best to help you solve the problem .)