Not sure about Forscan. Normally you would use FDRS to run AWD - PMI. Then update the As-Built AWD module using FDRS also, selecting "connector present" on the FADA option. Worst case scenario, just go to the dealer and say you installed a new AWD module and need the PMI/update performed. You would still save money on diagnostics, AWD sourcing and installation.
Not sure what "calibration" through forscan means, but in my mind, you need to load the As-Built file for the AWD module and update that to the new module. Then maybe reboot any and all modules related to the AWD module.
If the codes were AWD communication faults to start out with, sounds like the TSB for grounding the AWD module should have been attempted instead of getting a new AWD module.