Replaced transmission now it won't start

Replaced a transmission (AOD-E) on my sons 1994 Mustang 2.8l. Now it won't start. Starter doesn't even click. I have made sure all cables are on the transmission and the starter. Charged the battery over night to make sure it was fully charged. I tried to start it in all gears in case the cable isn't adjusted properly and transmission isn't truly in park(Neutral).
Also got under car and removed cable and manually put it in park (and all the other gears). Still wouldn't start. Also made sure that the torque converter and flywheel would turn.
I would appreciate any ideas that anyone may have.

Sounds like the auto park/neutral safety is not working. Check the connection going to the tranny make sure it's right look for broken wires on it etc..,

One of my first projects I was changing the cam and intake system on my 81 f100. put every thing together and the truck wouldent start. this problem drove me nuts. Turned out I made a rookie mistake of working on it with the battery hooked up and melted the fusable link. it looks like a regular wire and I dident solve it the guy i sold it to did. I still kick myself especially since I put all the time and effort then sold it after just giving up (another life lesson). I dont know where the fusible link is on your ride or if this is even the problem, but examine every possible problem no matter how remote. Good luck.