Gauge cluster replacement bricked my car

My gauge cluster went out on my jeep. I went to a
mechanc and he told me to buy one off eBay so I
searched up to make sure I got the right one. When
It came I didn’t have the money to take it back to a
mechanic so I tried doing it my self. I wasn’t aware I
had to reprogram the new gauge in order for the car
to run. When I tried to put the old gauge in, I guess
the computer is scrambled because now with either  
gauge, the car starts but quits 2 seconds later. Can
someone tell me what my next steps are