Garmin Edge 530 battery drain while turned off

Hello,

I have a problem with my Garmin Edge 530. The battery is draining while turned off.

I had the battery replaced. The problem is still there.
So i am sure it have to be a software issue.

Garmin software is up-to-date.
Already did install it back to factory settings and afterwards updated it again. Problem still there.

I am sure i fully turn it off every time i used it. Holding the powerbutton and select 'turn off'.

Battery after charging = 100%, next morning when i turn it on 85%.

Anyone have a solution?