MacBook Pro not turning on a little while after replacing battery

I replaced the battery in my macbook pro after the old one started expanding and stopped the trackpad from clicking down.

I bought a new battery from ebay and when i swapped them it worked fine. However i did notice that when i tried to boot the machine, sometimes there would be failed boot attempts where it would be stuck on the apple logo screen, other times the battery indicator would blink 5 times. Although if i tried it again or a few more times it would eventually boot fine into macOS. I checked the battery health and it said normal and nothing was out of the ordinary

After reading the instructions it said that i should discharge the battery to 2% and then charge it back to 100% but it warned me not to discharge it to 0% as it will damage the battery pack and shorten it's life. After discharging it to 2% it shutdown and now it won't start back up again.

I can't get it to charge as the light on the charger just stays green, and the only way it will boot is to run off of the charger power. The indicator light now always flashes 5 times. The battery wont charge and is most definitely at 0%

What should i do?