mmcblk0 could not be opened.
While trying to flash while keeping user data, flashdrive failed to startup giving the error:
/dev/mmcblk0 could not be opened, possible eMMC defect.
What version of jumpdrive is this using? It may need an updated kernel to be more reliable. Libremmanager was not able to detect the error, perhaps add a timeout if the device fails to enter jumpdrive mode.