Storad src 252-1 storage heater?

Please help if possible. This heater is in my son's rental flat. He has both wall switches on. He has kept the convector dial to 0 on the top left. The two switches on top right of the heater, with one and two dots respectively, are switched down towards the dots. It has been left for over a week like this to no effect. What are we doing wrong? Could it be that it needs a manual re set inside and if so, is it easy to get the cover off?
Should both wall switches (one fused, one not) be on? He has economy 7.
Thank you

Fi
November 2019