How can I fix my battery life on the Instinct?

My Garmin Instinct was working nicely at full capacity with long battery life for almost 8 months since I received it in December 2020. Now all of a sudden the battery life drains as rapidly as 24 hours or fewer. I've done a great deal of troubleshooting including talking to a Garmin help tech. who had me to delete some file folders on the device. This was not the problem apparently, nor was it that the charging ports needed cleansing. My watch continues to drain rapidly. I even adjusted some features mentioned in all the online battery life improvement tips, but again, it worked very well for nearly 8 months with days upon days of battery life using apps, tracking activities, receiving notifications, 20% backlight, etc. I also had a hunch that it was the GPS mode sapping the battery. I have changed every activity app to "GPS off" or ultratrac, and still no luck. What should I do to restore the regular 14-day battery life? Please help.