I will start from far away. In January, I put a new battery into my laptop, a few weeks ago it started to act strangely,...

A few days ago I have replaced the battery in my Macbook following the guide on ifixit, which involved taking out the...

For anyone finding this topic in the future, whoever has the same issue: Yes, the issue was with the battery, I just got RMA and the second battery replaced was working fine, it was charging quickly, not lagging when charging and not going to sleep by itself.