No power at all?

You mean disconnect the negative battery terminal the connect jumper to both battery posts?

Oh, had a thought about that just didn't know it can happen.

Sparks normally when the negative terminal is removed and with negative jumper attached, nothing excessive.

But if I also remove both battery terminals and connect jumper straight to them still sparks excessive.

With all fuses out except the 120 still sparks.

I am not seeing anything burned or weird under the box. But isn't the fuse which is snowing on bottom supposed to connect to something? Or is it just made like this to sit inside the box, weird that the end of the fuse which comes out of the box underneath connects to nothing. I am guessing the issue with the 120 fuse since it still sparks with nothing else connected and even with the battery jumper only connected to the jumper box.

More.

Also found out that the positive battery cable which has 2 leads going into the box one is negative other is positive.

Okay progress. I followed the positive cable that goes from the box to alternator, found a previous work was done on one of the coils which melted before the repair or after, disconnected the 3 front coils, no change. Kept following the sane wire to alternator, removed the positive cable which has a nut on the alternator and now it does not show ground on the 120-amp fuse. Connected all the fuses that I removed back and now it does mot spark, but no power inside other than interior lights, nothing when I turn ignition on.

Put in a new alternator, no more spark after I connected jumper, I have headlight so am good for now. Thanks