Siemens D 12-52 combi- dryer stopping, no heat

Hi,

Bought my combined washer/dryer Siemens D 12-52 5 years ago now.

Worked well until 1 year ago when paused and stopped half way through cycle.

Now the dryer begins and cycles for around 15 before stopping.
No fault number displays and the control panel appears frozen.
The door unlocks and the cloths are spun but not at all warm.

Any ideas?

Advice gratefully received !