How can i fix my Dimplex storage heater?

Hi all,

I have a Dimplex storage in my leaving room, which stopped working. The manual part is, but it doesn’t store any heat at night. I do not have the reference or any booklet to go with it.
I think it stopped working because clothes were put on to dry (oopsss)

When I checked the fuse box in the hall way, no red light was on during the night. I have been told, it should (not sure if this is correct or not)
I've read the forum for solutions, and found few about the reset trips.

I took down the front and top part of the heater yesterday.
I found the little "circular" white trip. However, I couldn’t take out the metal cover where the "input and output" sockets are. The screws seem damaged, or I’m simply not strong enough :)
I tried to push down the trip, without success and it actually felled off (I kept it). I put everything back up (without the trip) and turned on the storage socket on.
During the night, the red light was on at the fuse box. However the heater was completely cold this morning, and the red light stayed on, even after 8am, when I actually switch off the heater storage socket.

Did I do a bit mistake by completely taking out the white trip?

Any suggestions so my heater starts storing heat at night again?

Many thanks
Anne