Maybe I wasn't following but what is current state? Is it dying as soon as you remove the cables and it is still doing that or did you take it back to the shop and they found an electrical issue?
I think you are correct that something is shorting out the control wire for the alternator and more than likely it is the ECM. However, this can be confirmed by testing the voltage on each of the wires shown below.
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Monday, January 13th, 2020 AT 1:42 PM