There looks to be a few different concerns here, in which much of them can be related to WiFi interference. Video lag and audio interference can be resolved through optimizing signal strength. Check out your [RSSI in the device health section of the Ring app](https://community.ring.com/t/how-it-works-your-ring-device-rssi-good-vs-poor/229), to ensure for optimal wifi signal. I recommend also connecting to 2.4 Ghz WiFi rather than 5 Ghz, if not already. As long as you've installed the Video Doorbell Pro per the [instructions in the installation article](https://support.ring.com/hc/en-gb/articles/360036047831-Physically-Installing-your-Ring-Video-Doorbell-Pro), power should be sufficient. It is likely you've tried, but see if wiping the screen or inspecting further might help with the black mark, as that is odd to see. If these concerns persist and you need further assistance, please give our support team a call at one of the numbers available [here](https://support.ring.com/hc/en-us/articles/213608406). If you are outside of the US, please visit [here ](https://support.ring.com/hc/en-gb/articles/213608406)to see how to contact support.