Remote says Syncing 0% after 7 days of working fine

I programmed the remote for a customer and had everything working to their satisfaction. After a week or more of the remote working properly it suddenly went in to sync 0% and continued to stay that way for 3 days until I could get to the customer. We were able to press the back button and power to repair the remote. However, I would like to know what calls that and how to avoid it in the future?