Freezer showing high temperature light

I failed to defrost my fridge freezer for a long time and after a while when the freezer door could not close properly due to the ice buildup, the "freezer high temperature" light lit up. After defrosting the freezer, the light stayed on. What should I do?

Also, there is ice at the back wall of the fridge? What should I do to resolve the problem?

Thank you.

Is there a reset button on your freezer?

It is a Hotpoint Fridge Freezer. I don't think that there is a reset button.