Garmin instinct, battery and altimetry problem

Now i'm at the 5th day with three Activity recorded and the Watch Need to be charged, buy It should hang for 10 days or im wrong?...anybody can Say anything about this thing, there Is no difference between this Watch and the Forerunner 245!

In the last Activity the altimetry Is, at the end, -45m. It says that my house Is -45 Meter under the Sea. I live on the 4th floor.....why?