I've got an old laptop which is not charging or powering up. I've tested the power supply which is fine so bought a new power jack.

I've just pulled it apart but my trusty 40W soldering iron cannot melt the solder between the jack pins and the motherboard. It's only a Jaycar one I bought for doing a car stereo install last year. It's heating ok and melts the roll of solder I have so am I missing something ?

There also looks to be some damage to the motherboard itself. Around the pins to the DC jack it looks like dark brown molasses (in colour and it's glossy) but it's also rock hard. I cant scratch it off at all. I'm wondering if the faulty jack has damaged the board.

Any ideas on how I confirm it's the jack which is faulty without being able to take it off ? There must be somewhere on the board I can plug a multimeter in to.

Thanks