Battery % doesn't change. Need help to identify Components!

I have a very strange fault with a couple of iPhones. I regularly replace the rear housing of iPhones, I am very careful with the replacement of screws (correct screws in correct positions and not tightened excessively). I have successfully completed this over 50 times and consider myself fairly competent in doing so.

However, I have come across something which is very bizarre and has happened on three separate occasions now. Once I turn the iPhone on to test it the phone will blue screen and restart itself two or three times at random. Once this has happened the phone will function perfectly except for the battery % display will not change. Obviously this causes the user to not be able to track when it needs charging. The phone will run out of battery and the process will happen again.

It must be something I am doing to the phone, I am not overly fussed on finding a fix. Just a reason why this is occurring and how I can prevent it happening again in the future!.

Thanks in advance,

I have done some more research and believe that the issue may be an "FL 11 capacitor" could anyone confirm this and give me some info about what it does exactly and where I can source one to try and fix the issue?

So I have had a look at the logic Board under a microscope and have found that some capacitors have been knocked off when removing the battery. I think the one on the far left is a "FL 11 inductor" but I am not sure what the other two are. Could someone tell me what they are?

Good Logic Board :

Damaged Logic Board :