Replaced battery, machine keeps shutting down

Hi everyone,

I bought a replacement battery from ifixit and just fitted it into my MacBook Air late 2018 Model A1932 EMC 3184

I used the ifixit guide which was really helpful!

It does work! Which I am happy about! But I am getting a “Service Recommended“ Warning over the battery icon. Also, the machine shuts itself down every now again.

I have tried resetting the SMC, but i am not sure it worked as the screen brightness is not changed after my attempt (I assume it would get brighter if I did the reset correctly)

Any ideas what I can do?