Hello,
I also have lenovo y50-70 4k screen and i have replaced my motherboard because graphic chip died on it. My BIOS doesn't have info about serial number, MTM or product name as they are all listed as INVALID. I would be very thankful if somebody could explain how could i edit BIOS or how to create backup and send it to you so i can edit it. If you unlock it for me so i can enter my information instead of INVALID. I've tried to browse all forums and internet for weeks in hope to find solution for my problem but with no luck.