how can i find out what is wrong with my hotpoint aquaruis ctd40?

i have a hotpoint ctd40 and it has suddenly developed a problem. when i put in some drying it went all day and did not get hot at all i have emptied all the water and ensured there was no build up of fluff etc but when i restart it all the buttons are flashing red even though the dryer is still going round its seems that no heat is occuring what is this and how can i sort it out i do not have a manual as it was brought of my daughter with the matching washer and she could not find the instructions