Engine Overheat problems of the 2020 Hyundai Santa Fe

My husband and I purchased this car brand new, with only 252 miles on it. On the third day of owning it we were driving and within 5 miles the car began alarming with the center driver console indicating the engine was overheated. The temperature gauge was in the red zone. After a few seconds it dropped slightly and fluctuated in the upper 2/3s of the high temperature region. We drove to the dealership, which was within 10 miles. Once we were within half a mile the car engine began rattling every-time I tried to accelerate and the temperature gauge at this point remained in the redline. In addition, during all of this we turned the heat on to pull some heat from the engine but only cold air would blow. We were within the 3 day grace period of no questions asked return policy so we decided to return the call as it was brand new and had such a serious malfunction. We have not heard back from the dealership as to why the car malfunctioned.