Not charging + showing after battery replacement

Good morning folks!

I have been using ifixit for years now and I'm so thankful for the detailed (high-res images) guides. Today I replaced the battery of an MBP mid 2017 (2-TB, 13") but somehow it does not work. It is not recognized and so not charging/working.

Here is what I did: I followed this guide and used a replacement battery from manufacturer (HASESS) which is used to replace part A1713.

When I try to power on the MBP without a charger connected it shows the "Please charge/no power left" symbol. When I then connect a charger it is booting like always. As soon as I disconnect the cable, the MBP is shutting down. When I check via Coconutbattery or integrated report it does not show a battery nor a manufacturer, cycles or anything else.

I tried to reset PRAM, NVRAM and SMC but this does not changed anything. I checked for the small battery connector cable and it is in place.

I hope you have got some ideas! Thank you very much!