now it wont start, vnl 780

Ok so i got me a new air compressor and now my truck was working fine, i was sitting waiting to get loaded in el paso and after about two hours i decided to be productive and install my inverter, i went to connect the positive to the batteries, and i noticed one outta the 4 posts had grip like it was made to come off by hand. There was three small wires connected to it like accesories with fuses, when i went to unscew the nut, the truck turned of, i freaked and put everything back together, i went to turn on the truck and nothing, the starter would go but it wouldnt turn on, so i started checking fuses, it just made things worst, now it dont turn over and my ultra shift console wont light up no more, what did i do??

 

I dont get scared by sparks, this #### volvo has my scared, so #### sensitive, i freaked out that it killed my engine and now it wont start

 

Theres more fuses?? I see three where the batteries are, and then the ones on the dash

 

Do i just remove the negative? Positive? Or both?

 

This is a 2007 Volvo vnl 780 with the D12 volvo engine