Answer: Germination should be very fast in this warm weather. To be honest, I'm not sure what happened but I suspect they dried out despite the watering. When you plant in summer and it is very hot and dry, you may find it works better to plant the beans a bit deeper than you would in the spring, then water very deeply but less often. That way you reduce the risk of the seeds drying out in mid-germination. If they dry out once they have begun to germinate, they will die.
On the other hand, your watering may not have moistened them sufficiently to germinate at all. (Watering, particularly during very dry weather, can be tricky. You may want to dig down a bit and see how effective your watering actually is.) You might try digging up a few and see how they look. If they seem pretty much the same as when you planted them, then you'll know they've stayed dry.
Then and again, the frequent watering may have rotted the seed. Finally, if you have never grown beans in that spot you might consider using an inoculant when you try again. This can be helpful in increasing germination and yield.
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