Macbook Air 2017 13" A1466 Shutting down randomly with code -128 after SSD and battery replacement

Hello,

one week ago I replaced my 128 GB SSD with a 1 TB SSD (using an adapter) and I replaced the battery. I transferred the OS and all my data from my old SSD to the new SSD with an SSD enclosure connected to the mac via USB and Carbon Copy Cloner.

The battery I replaced because the mac discharged noticeably more rapidly than it used to do.

A few days ago, the Macbook started abruptly shutting down (while not connected to the charger) at percentages in the range of 50+%. Yesterday, it even shut down at around 70%.

I already tied multiple SMC resets and tried discharging it as much as possible before charging it back up to full. After the 70%-shutdown, I was actually able to keep using it after turning it back on and charging it for only 2 more minutes. It eventually shut down at 20%, then I wanted to charge it back up to 100%. However, at 41%, it didn"t charge any more. Coconutbattery reported 0 Watts charge speed.

After un-plugging and re-plugging the charger a few times and multiple abrupt unwanted shutdowns (while plugged in!), I could get it to charge with a measly 2 Watts. I let it then recharge over night.

Today, even using it at 100% charge resulted in shutdowns while not plugged in. While writing this post I had three shutdowns already in fact, while at 95% and two of these even with with the charging cable plugged in.

Coconutbattery claims my new battery is fine (note this was taken a few minutes before it shut down):

I also tried resetting the PRAM with Option-Command-P-R while starting, leading to repeated chime sound every few seconds and what appears to be a restart loop. When I stopped holding the keys, it booted normally. I m not sure if I have reset the PRAM successfully, is there a way to check? I assumed a menu would come up...

Lastly, I also looked at the shutdown codes with the Terminal:

With shutdown code 0 implying it ran out of battery and code -128 implying some hardware issue.

Lastly, I held down D while booting to do an Apple Hardware check. This was the result:

This really makes it seem like a battery problem. I am also worried I might have damaged the logic board when opening up the MacBook, could this be possible?

I am thinking about putting the old battery back in to check if the issue persists. As I am currently travelling, I can only do that once I'm back home.

Has anybody experienced something similar? Any help appreciated. Thanks.