Battery not charging troubleshooting

Hello,

I have a strange problem with my Huawei phone: when I plug it in, it says that it is charging, but the battery percentage does not change. I tried everything from replacing the battery to trying dozens of different chargers from different OEMs. I think it must be a hardware problem with how the phone delivers power to the battery, and I would like to try to troubleshoot it myself if possible. So, my question is, what exactly do I need to look for on the motherboard?

I used a multimeter on the battery charging pins with the battery and charger plugged in, and I am getting the same reading (3.93 V) as I am getting from the battery itself.

Is there some guide somewhere related to this?

Thanks!