Installed new battery, phone doesn't charge and continuously restarts

Hello,

I have done quite a bit of work on my iPhone, so I feel fairly competent with my changes on it.

However, I recently replaced the battery (as the old one wasn't lasting through the day anymore), and I can't start it unless it is plugged into the wall (into a USB doesn't work).

Opon starting up the phone with the new battery, I get the Apple logo, it starts up, suggests that it needs to be activated and then just sits there. I have clearly tried to plug it into the laptop, but the second I unplug it from the power outlet, it shuts off... Even though the battery shows 100%.

I tried leaving the phone plugged in for a while incase the battery was actually empty but the battery indicator was wrong, but that didn't seems to help at all.

I did also do a hard reset, but that didn't resolve the issue either.

I re-installed my old battery, and it works perfectly fine. Tried the new battery again, and I get the same behavior. I have only found one other article on ifixit.com with a similar description but seems that the author there had actually damaged the logic board or something... (Installed new battery, wont charge, restarts repeatedly..)

Any suggestions would be much appreciated. I will be contacting the seller of the battery to have him confirm if it is defective or not and if he has any suggestions as well...

Many thanks.