how can i fix my zanussi TC7114W condenser dryer?

hi i have a zanssi TC7114W condenser dryer, i think we let the water tank get to full as the dryer would not start, i emptied the tank then took the back off the dryer dried and cleaned all around the area, but the dryer will not start, the start button will not stay in and i noticed that as i push the button in the light glows brighter and when i take my finger off the button the light go's dimmer, we had this oroblem once before a guy came out and fixed without the need for any new parts so i am wondering if there is some kind of cut off switch,any help much appreciated thanks. john