If none of the troubleshooting steps work, what is the next course of action for the E425-B301 error?

If you've tried all the troubleshooting steps and the E425-B301 error persists, it's likely a hardware issue requiring professional repair. Contact Epson support or a qualified scanner repair technician for assistance. They may be able to diagnose the problem more accurately and offer a repair solution or recommend a replacement scanner.