Hi @Sam Grant Greetings! Welcome to Microsoft Q&A forum. Thank you for posting this question here.
Based on the details you mentioned and the steps you have tried, it sounds like the device ran into a hardware issue. Just for reference, please look into the steps provided in the article Reset Azure Kinect DK The reset button for the device can be found as indicated in the picture below.
If the device does not reset even after following the correct steps, please create a support request with the services team through the link - Get help for additional assistance on this.
If the response helped, please do click Accept Answer and Yes for the answer provided. Doing so would help other community members with similar issue identify the solution. I highly appreciate your contribution to the community.