Cut out while driving would not start

Had this car two months and until today I have had no problems. Left work tonight and the car started no problem. When I went to put on the air conditioner on nothing happened. Fan/vents were not blowing and I also noticed that the light that comes on when air conditioner button is on was not illuminated. Next I noticed that my regular dash display was not on. Tried switching my headlamps on and the dash did not illuminate. CD player was working fine. When indicating the indicator lights blinked as they should do on the dash. After a couple of miles I leave the dual carriageway and enter into a residential area. Within one hundred yards I suddenly lose all power, all the red warning lights on the dash come on and the car quits on me. There is a little white smoke from under bonnet (passenger side) and car will not restart/turnover. It has a burning smell. Hazard lights work. Car is towed to garage who have suggested I need a new starter motor. Whilst this may well be true I do not see how that would have made the car cut out?