Solved - I created a bootable USB MacOS install and was able to erase the HD, reformat, and reinstall MacOS. During this process, i found out it was recognizing the internal keyboard/touchpad. After some diggng, the keyboard/touchpad ribbon cable was not fully inserted when the motherboard was swapped. This explained why all of the keyboard holding combos did not work. Once reinserted, the keyboard combos worked, was able to reset the SMC, and then everything was installed, completed and updated.
Works great now.