Cooling phone case for Arizona
what about a case for phones with fans and spare battery>
I do postmates/Door Dash and have been thinking of picking up instacart. But while doing it here in phoenix with crappy AC, my phone starts to over heat and want to blow up. So I stopped at a store to see if there was a case that helped with that and found out there isn't. And I know laptops have all sorts of stuff like this so why can't phones? So since I know they have cases with back up batteries in it and fans that you can buy that are small. Why not just combine them?

This idea's problems
The cost for developing something like this is as follows.
Design and non recurring engineering, NRE, perhaps 10,000 dollars.
Then if you order n of those, the cost would be around 40 dollars each for 1,000 orders. So initial cost is 50000 dollars. Patents in two countries, about 5,000 dollars. Then it is to marketing. If you sell those babies at local mall stores, say 90 dollars each, the stall owner takes 40 and you keep 50. Your profit margin is 10 dollars each unit. So you just spent 55000 dollars to make 100,000 dollars, but you need to quit your day job to promote this.
At this point, competitions would have noticed you. They will drop the price of this baby to 20. So you need to either keep your original price (which is hard) or lose money.
Some suggestions on improving it