Erased macbook air M1 using Find My, now cannot access it following repair

After dropping my Macbook Air, my screen went black so I had to have a repair done with my insurance. As the creen was black I couldn't do a conventional reset so I used erase in Find My, in order that my personal details etc. wouldn't be on there while it was away. It's been repaired but the opening screen is asking for Name and Password. My previously used name and password don't work so I contacted the repairers who say Name and Password screen was as it arrived with them. What screen would I expect to find showing after using Erase form Find My?