xFinity XB8-T modem stopped working 3 days after install.

Before move in date of my new place, I got a new modem installed. Coaxial had to be moved and replaced because it was dead, so they put a new one in. Come Saturday, stopped working. I have both called support and chatted with agents and ill troubleshooting possible. My tech appointment is scheduled three days from now so I’m trying to figure out if there’s any other troubleshooting I can do to avoid the wait. When I unplug it and we plug it in it flashes, red and yellow and then finally it goes to a solid orange light. I am pretty tech savvy so not sure if the box is bad but I don’t have a retail store near me so cannot go and replace router. HELP!!