My battery is malfunctioning

That sounds like a failing battery rather than a software issue. If it stays around 5% and shuts off when unplugged, the battery may no longer be holding a charge. Try a different known-good charger/cable, but if nothing changes, I’d replace the battery.That sounds like a failing battery rather than a software issue. If it stays around 5% and shuts off when unplugged, the battery may no longer be holding a charge.

Try a different known-good charger/cable, but if nothing changes, I’d replace the battery.

@luyandamadlala that indicates a bad battery or a bad charging board. It is most likely the battery but since you have to disassemble your phone anyway, you might as well change the charging board and the battery at the same time.

Since iFixit does not yet have a specific guide for this, use something like this video to work on your phone. Batteries and charging board are readily available.

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 the same issues with their device. 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!