After installing a new transmission, nothing happened, the headlights, dome and dash lights did not work?

I would look for a ground wire or strap not connected or a wire that was pinched during the transmission replacement. There are at least three primary ground points on that side of the engine compartment with grounds 29 and 30 being the ones I would suspect in this case. I would also check the battery to body ground cable. A quick check for that would be to turn the lights on and use a jumper wire from the battery ground to the engine block, then to a bare metal spot on the chassis. If the lights come on you know it's a ground issue.

https://www.2carpros.com/articles/how-to-check-wiring