F10 error code on 3yr old CTD85 Hotpoint Tumble Dryer?

Have a 3yr old Hotpoint CTD85 Dryer, had an F10 error code 1yr ago and an engineer charged £35 to fix it. The error code has returned and I have tried all the advice on this site. However, I cannot get the back off. Tried to take off various bits but they never reveal the inards of the machine let alone thermostats.

Tried to take the entire back casing off but again it became to complicated to take apart things and not know how to put it back together.

Can anyone help and be more specific, have the designs changed or am I missing something? Are the Thermostats located top or bottom?

Please help!