Need help with 96 international

[Watrshed]

Howdy y’all! I have a 96 international Thomas 3600 with a Navistar DT466. I recently tried to start it and it starts, but the engine doesn’t stay running when you move the key back.
Which is weird because it used to just a few months ago and it had been sitting for two years before that.
I had a mobile mechanic come by and tell me it was the ignition solenoid and I went and got a new one but am unsure about wiring it and want to make sure I do it right.
Would really love some help on this.
Also, just realized my kids had taken out a couple fuses when they were messing around on the bus so just now realizing that’s probably been the issue all along.
But still, now I have a brand new solenoid and want to make sure it’s connected properly.
I hooked it up the way I thought it was before but it shot a spark when I turned the engine over so I don’t want to make things worse, any help would really be appreciated.
My bus is already registered as an rv with a stove, bunk beds, shower, etc etc as well as hardwood floors and cherry countertops! Really wanna take her out on some camping trips as we hope to use her as a place to live next year.
Thanks!