Hi @KirstenP,
Thanks for reaching out to the community! I understand your concern about what to do if you lose the battery cover key for your Nest Yale Lock. Let me share some information with you.
If you lose this key, you can use anything that fits into the hole on the battery cover, like a paperclip or something similar. Thanks for trying the Allen wrench as well; as you noticed, it's a bit too big for the hole, so a paperclip will be a better fit.
I hope this helps! Keep me posted if you have any other questions.
Best regards,
Debora
