Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Is your Sentry Fire Safe's battery holder like this? (I find it difficult to be quite sure that I am finding the right thing for you, at this point, it is a little uncertain):
If not, I will try to find the right thing for you - if it is right, or looks like the right replacement, please let me know so that I may close my search. Thanks.