How to replace charging system?

@piousmavuso9647 you are not telling us what the issues with your "charging System" are. For now, I would suggest you replace the charging board (sub_board). Since iFixit does not yet have a guide for that, use something like this video to work on it.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!

If you're talking about replacing things like the charging port then yes, that can be done. The parts I'd be looking at would be what's called the auxiliary or daughter board that the USB port is mounted on, plus there's an interconnect cable that provides the connection between the motherboard and the daughter card. The following guide should give you all the information you would need to replace either or both parts.

Manuales / Huawei P Smart (2019) / Auxiliary plate - Nadie Me Llama Gallina

If you're talking about something like the power management chip, that's an entirely different subject. Replacing components like that mounted on the motherboard requires microsoldering expertise and equipment that is pretty far outside the skill set of most DIY-ers.

If I've missed something or misunderstood what you're trying to do, feel free get back to me in the comments and clarify what your goal is.