<human>: Can you provide a brief rundown of the text in within 3 sentences?

Hi all, I'm really desperate for some help here.

We picked up our rescue dog Kenny from his carer today and as soon as he was off the leash in our back yard, he got super scared and runs away at the sight of us. When we met him the first time, he was fine with me but wouldn't go near my husband then when we picked him up today he was jumping up on both of us and really affectionate. He was also really good on the car ride home, just really chilled out. As soon as he got to our house and after he had a sniff around, I let him off the leash so he could explore and do his thing. He came up to me once or twice when I called him, but now he runs away at the sight of us. and won't let us near him. We tried tempting him with food and his ball, but he's not interested. Something in his brain just switched from "These people give me pats" to "RUN AWAY!" in about 5 minutes while we were just sitting in the yard watching him run around and wee on everything. We've tried calling his carer but the calls keep going right to voice mail so we've gotten nothing from her yet. I did some Googling and we tried approaching him with food quietly and averting our eyes and I even tried just sitting on the ground quietly looking away with food and he just stared at me the whole time. My husband is just on the phone now with our regular vet getting advice as well.

A bit of background on Kenny: He's a 3 year old Border Collie x Husky. His carer said she believes he's from a home where the father of the family used pretty severe positive punishment.
<bot>: 3 year old border collie x husky went from really friendly to terrified in about 5 minutes of being brought home. Hasn't been aggressive, but runs at the sight of my husband and I.