Hi
Sorry that all that time has gone.
I suggest that you use the B2 to format the memory device.
Press/hold B2 STOP button until "SAVING" appears and then changes to Clock display.
Turn off power.
Wait 30 seconds.
Insert the memory device into USB port A (or C)
Turn on power.
Wait for B2 to finish booting up.
Menu > Settings > Maintenance > Format USB A (or Format USB C)
If formatting is working correctly the display will briefly say "Partitioning", followed by "Formatting" which should stay on screen for 10 to 20 seconds and upto 1-2 minutes.
If the display briefly says "Partitioning" and "Formatting", then try again the menu step again.
Press/hold STOP button until SAVING appears and then changes to Clock display.
Turn off power.
Wait 30 seconds.
Remove the memory device from USB port.
Load music files onto the memory device ...
Steve