boche wte86304gb/05

Hi.Problem with this condenser tumble dryer is that it will not start,no digital display,no nothing,power into m/ch.When i quizzed the customer, she said that it will run up to 20/30 minutes then shuts down as described above and then will restart if left for 2/3 hours,so i caught it in one of its break down modes! No problem with float box,o/load resettable stat ok,door lock m/swt “clicks”…..help!!!We are new to working on this bosch stuff and i`m afraid i`m a little lost,any ideas folks please???