Hi and thanks for using 2CarPros.com.
Based on your description, the problem is at the battery terminals. I have a feeling the problem may be related to a loose or corroded connection. What may be happening is when you attach the jumper pack, it is tightening on the battery terminals and allowing there to be a connection. When removed, the connection is lost. First, follow this link and see if it helps.
https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked
Try that and let me know if it helps. If it does not, tell me how you are attaching the jumper pack. Both cables to the battery or positive to battery and ground to a different grounding location.
Take care and let me know what you find.
Joe
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Thursday, October 4th, 2018 AT 7:31 PM