Bought a 2012 386 with bad ecm

So i bought a 2012 386 paccar mx13 with a bad ecm(pulling j1939 code). First order of business was to take my buddies ecm from his kenworth that he has sitting and plug it into mine. Plugged it in and took me 45 min to get it to fire up only because previous owner had the fuel system opened. I decided to switch the ecm back to the old one in hopes that it would mercilessly fire up and to my luck it didnt so I switched it back to my buddies ecm and now it won't fire up. So my bro suggested I take both ecm and plug them into my buddies kenworth and see what happens, I plugged my ecm first to see if it's really bad and yes it is, pulled a j1939 code then went to plug his in that came originally from his kenworth and it's also pulling j1939. Did I fry my buddies ecm? Do I have a short on my peterbilt causing the ecm to get fried? Thank you guys.

 

Dash sais j1939 engine failure, searched online and it has to do with the ecm going bad

 

Ok so I bought a scanner and pulled this code(pic attached). Issue is I'm getting this code from the "brake" category. engine, trans, chassis etc. Is not pulling any codes that would have to do with the ecm, I'm not getting codes from any category except the brake category. Thank you guys