I put my amp meter inline with battery and after 10? minutes it went to showing 0.1amp drain .... just fine!

So bmw battery installed by bmw 18 months ago was tested at oreilly autoparts and their tester said it is bad.

Oreilly connected to underhood jump-charging point and now I have a check engine with message that there was a significant discharge when the car was off. How do I clear that?

So I guess I need to register a new battery ..... I guess in disconnecting battery for two days to work on oil cooler gasket replace 2+ months ago the battery lost it's registration and then the charging system in last 2-3 months damaged battery?