No power on Mazda Tribute

I have a 2004 Mazda Tribute which just stopped in the middle of the road the other day. The engine was still runing. I was able to drive it 1 block to a parking area, but it couldn’t move more than 5mph. My husband went back for it, had the same problem and brakes weren’t working well. No signs of problems before that, no indicator lights were on. Had a 45k mile tune up just 10 days before.

Had the car towed to the same dealer that did the tune-up and he said there’s nothing wrong with the car. They did a full diagnostics and drove it a few times since they got it (1 1/2 days). Do I just take the car back and keep my fingers crossed that it doesn’t happen again?