Normally, the car will charge the low voltage battery from the main battery. But, if the low voltage battery is depleted, it might not have enough energy to activate the contactors.
To get around this, you can connect a 12V jump box to the jump start terminals to provide enough charge for the car to activate the contactors.
Learn how to properly tow and jump start the vehicle in the unlikely event your vehicle runs out of range.
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You should disconnect your aftermarket equipment until you determine what went wrong.