It sounds as if you've run into the PrecisionHD 1080p 4x S2 Camera Does Not Boot Due to Software Image Corruption issue, and because you're camera is already in the failed boot state the only solution is to contact TAC and RMA the camera.
Once you have a new camera and to prevent the issue from happening again, you should upgrade the SX20 software, the current software versions to date are TC7.3.7 and CE8.2. Because you're running TC5, you'll require a release key in order to upgrade the software, the endpoint must be on an active service contract in order to obtain one. Release keys can be requested from the Cisco Licensing Portal > Get Other Licenses > TelePresence Software Release Key. Note, once you upgrade to TC6.1 and later, a release key is no longer required to perform software upgrades, just an active support contract to download the software is then needed.
Something you'll need to consider if you want to stay on TC software or upgrade to CE software, there is a good diagram in the CE8 Release Notes that can help you in making that choice. In either case, be sure to reach through all the release notes of the various software so you're aware of any changes in features and behavior etc.
If for some reason the SX20 isn't on an active service contract and you're unable to get a release key, you can contact TAC with security advisory cisco-sa-20160504-tpxml and they should be able to provide you one so you can upgrade the software.
