Reporting
High heat might have

High heat might have something to do with it; in high heat, the plant is under a lot of stress. Leaves and fruit may develop sunscald (browning).

 

Another possibility is that there is poor pollination. In heat, bees are less active. Sometimes a poorly pollinated plant may develop small or misshapen fruits, or fruits that brown.

 

Overwatering might also be an issue--although you need to make sure the plant gets enough during high heat, it can not sit in water. Let it dry out about an inch or two deep before rewatering; give about 1 to 2 inches of water per week. Cut back on the watering a bit after the fruits appear, to improve flavor.

 

Check for pests and diseases as well--are there any other signs on the leaves, stems, or roots? Holes, browning, off-color, nodules on the roots, etc.?

 

If it is poor pollination, there is time to remedy it, since you still have lots of flowers--there are male and female flowers. Heat stress--it depends on the vigor of the plant, whether it will recover; provide some shade, such as with burlap screens, if you have high temperatures again, and lay down a thick layer of mulch. If you have signs of pests/disease, you might bring a sample in to your local garden center for ID and control options.