Symptoms:
The MSAC is not showing in the installer app and/or there are no lit LEDs present on the MSAC, next to the LV terminals.
Troubleshooting Steps:
The LV terminals in the INV are powered by the HPS so power cycling the Inverter or using SYSGUI to power cycle the HPS can reset the HPS.
Double check the CAN wires on both sides to ensure they are stripped correctly and fully landed.
Use a DMM to check voltage on 13V to GND at the MSAC side. This should read 12/13V.
If you suspect a break in the CAN cable, run a new CAN cable in open air between the INV and the MSAC. If the MSAC is powered by the new CAN cable then that confirms a break in the original CAN cable.