Assuming she replaced the watch battery with the correct size replacement, and also assuming the watch came in with all screws properly installed, I don’t understand how she could claim there was debris in one or more screw holes preventing her from full proper reassembly.

Random debris doesn’t find its way into a hole occupied with a screw. I feel like she might not have the proper skill and dexterity to work on such small things and might have accidentally crossed the threads, or something. 🤷