i used jumper cables on my 89 gt and heard a pop and everything is dead not sure where to start looking the battery had just gone down from no use, i didnt ground to chassis
So is the battery the problem? They were named Die Hard for a reason.
If you put the charger in 10a mode and have the clips connected to the cables (with one side off the battery), the older style (not digitally controlled and for AGM battery) chargers will have enough current to light up your dome light, probably the dash lights in the run position, and start testing for voltage with either a meter or a test light.
With the pop, did you see or smell the magical electric smoke? I still suspect a fuseable link, bad wire or ground.