It's been reported by Hueblog that the latest firmware update for the Philips Hue Bridge Pro appears to be causing significant problems for a number of users. Alongside reports on Reddit, users are describing that after installing the latest firmware update, the Hue Bridge Pro becomes completely unresponsive and displays only a solid red status LED.
Unfortunately, the issue seems to be fairly serious for those impacted. According to Hueblog, restarting the bridge doesn't resolve the problem, with the only solution currently being to have the Hue Bridge Pro repaired or replaced by Signify.