Battery hack needed

[2019 Equinox]

We tow a 2019 Equinox behind our RV using a Roadmaster tow system. Two years ago, it went dead while towing. We put a charger on it, still would not start after being fully charged. We called AAA, and the repair guy said the battery was fine.. He did some kind of hack by touching something underneath the hood around the battery with a screwdriver. The car started right up. He said sometimes when the battery goes low you have to do that to unlock the system.. Does anyone know what he did?