Battery percentage constantly changing sometimes does not turn

HI guys,

As the topic says I have an iPhone 5s which acting weird. Battery percentage is fluctuating sometimes does not turn on or charge.

Now some background information. Originally I was trying to replace broken screen and before doing that I disconnected the battery connector. While doing that I think I have shorted something as I was using metal tweezers (I know not very smart) and saw small spark. My assumption is that I shorted battery connector pin 5 (which is according to schematics is PP_BATT_VCC_CONN) to ground. It could also be other battery pin 4 (AP_BI_BATTERY_SWI_CONN).

So far I have measured all the caps and one filter near the battery connector and they are fine.

My guess then is that I damaged something in battery internals or is it something more serious?

I appreciate if you could help me with this issue.