Nokia Lumia 520 Battery Connector Jumper Ways Solution
https://gsmfixer.blogspot.com/2016/03/nokia-lumia-520-battery-connector.html
Nokia Lumia 520 Battery Connector problem occurs when there is a water damage on the connectors and some times there be a breakage in the connector so best solution is that you should change the battery connector and check your phone.
If the problem is still there then there must be problem in the motherboard lie missing lines etc so making jumper can solve this problem well. In the diagram here is Nokia Lumia 520 Battery Connector solution by making jumpers. Analyse it well and go for a solution.