Zanussi ZDF290X bottom fan oven not working?

We have a zanussi built in oven, model no-ZDF290X. Initial problem was no heat, no light but red indicator on the control panel coming on. Replaced the element and bulb and oven heated up. Thought it was fixed but then it tripped and now no heat, no light and no red indicator light. I'm thinking it's the thermostat that's gone and it has tripped due to overheating. Questions are -
Is it likely to be the thermostat and if yes and I replace it is there a reset switch in the rear of the oven to alow it to be used again? Also, how do I gp about changing it out, are there any videos/instructions to follow and any areas I need to be mindful of. Hope you can help!
Cheers
Andy