Remember to format the EXTERNAL (USB connected) hard drive using the B2's tools to achieve this. Doing it another way seems to lead to more problems - also remember that any formatting of a device erases its existing content!
Note that a USB drive formatted by the B2 will be "seen" OK by your PC but the PC may moan that there is something wrong with it and offer to repair it. DONT DO/ALLOW THIS REPAIR the device is perfectly OK to use as is.
It is not difficult to flash an SD Card, you will feel proud when you achieve it. Belena Etcher is a dream to use (remember DO NOT unzip the B2 file you download, Etcher will handle it AS IS).
Also B2 USB A is a better port to use than C for attached drives as it has slightly more power available to it.
If it all works, the first thing (after ensuring the B2 is attached to the WiFi or Ethernet cable (but not both at the same time) OK) is to do a Web Upgrade followed by a graceful (Press and Hold Stop/Play button until "saving" appears) power down. then reboot.
You may Then want to do a "Scan Disk " and if this works your B2 will be back in full working mode.
Fred.