I just bought a used Anet A8. All movements and heaters work but I cannot access the SD card because its menu selection is missing/disabled.I think this may need to be enabled in the CONFIGURATION.H file. Can a new CONFIGURATION.H file be uploaded somehow without replacing the complete firmware? If so, how?I have no backup files for the printer, only a PC and Raspberry Pi to connect via USB.I am new to 3D printers, so any help would be appreciated. Thank you.