You didn't say whether there was voltage on the charging pins. You should
start by tracing backward from the pins.

Also, it is not normal for a properly-specified resistor to be blackened (or
even darkened) by heat. This resistor should be replaced by one of the
correct value and wattage rating.

I realize English is not your first language, so I wanted to note that
plurals do not have apostrophes. For example, pins, not pin's.