My TiVo BOLT+ (3TB, cable) has locked up several times. When this happens, the BOLT+ does not respond to commands and rebooting it (via power off/on) shows a black screen (no video output) and sounds of the hard drive running, but nothing else. Most recently, the lockup began while I was deleting recordings - some individual, some folders. While power off/on immediately after a lockup doesn't help, I have found that letting the unit sit idle (and powered on) for several hours (e.g. overnight) clears the lockup. My BOLT+ is running the new software version 21.7.2.RCD-USC-11-149.