I highly encourage you to lurk around various internet forums. Garmin's own here: https://forums.garmin.com/ and Garmin subreddit is also very good: https://www.reddit.com/r/Garmin/. I read them regularly. Maybe you tried to test or turn on various functions. Maybe the firmware is not up to date and the watch is not trying to update. I would also recommend to shutdown and restart. One function that takes a lot of battery is 24/7 PulseOx. I turn it off. Connecting to phone GPS also takes some extra battery and complex watchfaces, too. But I can remember when I started and everything was turned on, which I later turned off. I can go from 100% charge to 10% in 10-14 days with the Venu 3 and I do not leave it plugged in, until it gets down to 10%. Good Luck.