Firmware update for motion sensor won't apply

One of my motion sensors is showing a firmware update available. I’ve tapped “schedule update” in the Ring app (with the system disarmed) and it shows “updating” and a percentage. I’ve never seen the percentage go past 6% before it either stops or starts over. The percentage changes are also very slow (several minutes for a 1% change). All of my other Ring Alarm sensors are showing as up-to-date, only this one motion sensor seems to having a problem. Battery level shows green. What can I do to get this firmware update applied?