So this goes back to the previous issues of losing the entire SPI flash filesystem on express boards in low power conditions. With the latest 2.1 firmware I've noticed it unfortunately still occurs, just now I plugged in a JST battery to a cplay express with 2.1 and it erased the entire filesystem (was left with a blank root and boot_out.txt file). Talking in chat one possible explanation is that jittery power on startup could cause a filesystem erase from brownout conditions. This fits my repro.. when I was plugging in the battery this cplay express has a very tight JST connector and required a moment and extra firm wiggle to get seated properly. During this time most likely the power was browning out or in an erratic state. Perhaps should consider delaying a FS erase and checking voltage before it occurs?