I had to come here and mention I got the same error, but once I closed my drive bay it worked (a.k.a. my disc drive was open). Once I closed it, I chose the same WH16NS60 1.02 firmware, and it was successful. I think I still checked the ENC? box too.
Thanks to everyone who worked on these tools (firmware and SDFlasher). I'm back in business with MakeMKV...
Regards,
T