Setting up a new hexcopter, using a recovered Cube black that was in a crash. Everything seemed to be OK on the new setup, however I was finializing the basic configuration and testing without props. I was able to resolve all the errors/faults except for Prearm : Logging failed. I swapped the SD card (16 GB for 16 GB), did a low-level format, on both Mac and PC. I checked the various LOG_ settings and they were set as they should be per other posts. My thinking is that the SD card carrier may have been damaged by the crash, but just wanted to see if there was anything else I could try before I buy a new cube.
You can try to put some dummy log into the SD card
E:\APM\LOGS\00000001.BIN and see if you can download it via Mission Planner.