Crank, start, no communication?

There are a few ground wires that need to be checked at the bellhousing. Can you please recheck the connections? Also check the fuses as well.

Here is a guide to help and the fuse locations as well:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the images (below). Please let us know what happens.

Which bellhousing? Is there a ground wire to the transmission?

Yes, there should be a ground wire at the bellhousing bolts if not you may have had a voltage spike when the battery was connected. Did you check the fuses? If they are okay, it sounds like the BCM when out but to be sure we should do a CAN scan which is easy. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is the location of the BCM and how to replace it in the images below. Check out the images (below). Please let us know what happens.