Yes you can 
On the printer screen go to Settings then to LAN Only Mode click it but don’t turn it on, make note of IP address and access code then return to home screen
Open your preferred FTP client (I use filezilla) and open an access to host: IP address of your printer, user is: bblp, password is the access code of your printer
Use implicit FTP over TLS
Don’t fill the port number it’s OK without it.
Edit: If your FTP client really requires it, use 990 as port number.
You’re done, you can now connect to the USB files
PS: You can use the above credentials to MQTT connect to your printer using MQTT Explorer if you like to see the commands sent to your printer. I can tell you how to do it if you’re interested 
PS2: Anytime you do a factory reset, the access code will change and the IP address may (just may) change as well if you did not hard set it in your router, so if you cannot connect after a reset, it’s normal, just change to the new access code (and may be IP address).