My 2008 A4 Avant has decided that it does not like Hot Weather! Yesterday I went out it started fine but when it was time to retune home it would not start. The ignition came on but on turning the key all dash lights stayed on, with no clicking from the starter motor, as there is with a flat battery.. This is not the first time this has happened it did during the last "Heat Wave" but returned to 'normal service when the weather changed! Anyone got any ideas of what may be the cause?