starting battery question

We took our 2010 Prius in to the dealer for a recall on the brake system. The recall was completed and we brought the car home. Two days later we went to start the car and the car and after pushing the start button the display was dead. I tried this several times and it would not do anything. I got out of the car and actuated the lock, unlock on the key pad and it would lock and unlock the doors OK. I got back in and the car started OK. 5 days later the same thing happened but this time the display come on OK but the car would not shift and the orange flashing light was activated. The display said to  put the park brake on before opening the driver door. The driver door was closed at this point. This was done several times with the same results. The windows worked fine! My wife got out of the passenger door and closed it and I tried the power switch again and all worked OK. I called the dealer that did the work and the service manager said that it was nothing they did and to bring the car back as they thought it needed a new starting battery. I questioned this as I have been a mechanic for 50 years and never had a battery that was dead and then be OK again. Anyway we did as told and $291.00 later we exited the dealer with a new battery. This has me wondering as it the car seemed to act like it had a loose connection at the battery or someplace else. This car has never given us any trouble or has never been back for repairs until  they touched it.
Your feedback will be much appreciated.
Thanks
Bill