Abandoned?

We were so happy with the blackbird breeding so close.
Today, whilst she was briefly away, I managed to get a picture of the (first) egg (using a selfie stick, my arms aren't long enough).
It looked so promising, in the extra you can see mama blackbird in the nest. But since some time later afternoon, early evening the nest seems deserted, no one keeping the egg warm.
I am not a chicken expert, but I assume that 17°C is not enough. It was 25°C until sunset, but now at half past 11 it is 17°.
So we fear that something happened. We will know more tomorrow.