Fermentation has not started

I brewed a SMASH on Saturday, and for a variety of reasons, I had a difficult time keeping a consistent 154 mash temp on my stove top. I forgot to take the grain off of the heat when I added it to the 170 degree water, and it made it up to 180 before I removed the pot. It took about 15 minutes to get the temperature to 152, but then had difficulty keeping it above 150, especially during the last 15 minutes of the hour. Everything else went as planned and I pitched the US-05 yeast.

It's three days later, and I have seen little to no active fermentation and it seemed to take an inordinate amount of time for the yeast to settle on the bottom. Did the temperature fluctuation thwart the release of the fermentable sugars? What else could have gone wrong? Should I dump the batch?

This was my first time using US-05 and I followed the directions on the package. Thanks for the help.

If I'm reading this correctly you got your grain and water up to 180 at the begining of your mash?? If so, that could play a role in your fermentable sugars.

Wait it out a few more days. What temp was the wort when you pitched the yeast? What is it now?

Take a reading with a hydrometer. If it's still the same time to consider repitching more yeast.

I've never mashed that high so I have no idea how much, or if any conversion happened at those temps.

"Activity" is not a good indicator of fermentation, gravity is. Take a hydromter reading.

I only mashed at 180 for about 3 minutes before I got it off the heat. The wort was at 70 when I pitched the yeast, and it's still around 70.

At 180 the amyl ease enzymes would be killed