Loud Engine Noise problems of the 2016 Toyota Prius

I previously sent in a complaint but there have been developments and I needed to explain more clearly. Our Toyota has less than 18,000 miles and has been very well taken care of. Despite this, our vehicle has not been in operation since earlier this month. It started by flashing warning lights 2 weeks ago and then wouldn't start up. Saturday when I opened the driver door to get something out of the inoperable vehicle, this initiated a very lengthy terrible sound coming from under hood on driver's side. It sounded like something would explode under the hood. This horrible process appearantly drained the whole battery. It has absolutely no signs of life now. All of this happened while the vehicle was stationary.

When comes to a stop and on acceleration vehicle won't move especially after rain and car wash. It happened 10 times since June 2017 and once a week lately. Every time it starts with loud noise from engine,right after that the battery bar dropped from full bar to one bar quickly in one second. If I have to stop at the traffic light when this happens it won't move. Early this year 01/12/2018,it 's being towed to puente hills Toyota dealer and service couldn't find any clue after 5hrs. On 06/01/2018 we brought it in again for same issues to the same dealer and being told no clue after 5 hrs again . On 06/06/2018 at 18. 38 pm pst, it happened again. . I feel so unsafe to drive, it might get me killed anytime when it happens,.