GOOD EVENING I WORK FOR BURGER KING AND HAVE A QUESTION FOR YOU ? WHEN WE TURN THE OVEN ON FOR THE FIRST TIME OF THE DAY IT WILL PREHEAT AND SAY READY. THEN IT WILL LET ME USE THE PRESET TIMER 1-9 AND SHELF A - E . THESE TIMERS WILL WORK ONE TIME THEN THE LCD READ OUT WILL SAY "CONT" AND THE REST OF THE DAY THE TIMERS DO NOT WORK OR THE SHELF BUTTONS. WHATS WRONG? HOW CAN I FIX THIS PLEASE?