My IPhone will not charge and it’s also say I have a unknown part in its battery

Hello,

Check the charging port for lint or other debris and see this:

If your iPhone, iPad, or iPod touch won‘t charge

Also see:

An "Unknown Part" message will be displayed if a part installation is incomplete, the part was replaced with a non-genuine component, the part was already used or installed in another ‌iPhone‌, or if the part is not functioning as expected

What is the battery health?

iPhone Battery and Performance

Good luck.