Finally found a fix for my iPhone 5. It seems to be working.----
Let me tell you what DID NOT WORK. Changing out (replacing the hardware) the camera-flash module, did not work. Doing a full restore to factory fresh, with no software, did not work. Turning various settings on and off with the camera and flash did not work. Pulling the case off the iPhone, did not work. Installing a new Iphone camera application, did not work.
Turning off the GPS link to the camera, and waiting a couple minutes with that off, WORKED!!!! Making sure GPS selection for the camera remains off, seems to work to keep the flash functional.
So it is the IOS9 upgrade (and rumor is that some have the same issue in older IOS 8 and IOS7 upgrades). Apple has not acknowledged the problem in any context, and will attempt to have the repair store sell you a refurbished replacement for $200 or more.
My suggestion is that there are several ways for the flash to have issues, but the user should keep trying them all before spending $200 for a replacement that might not work. And I wonder if apple store would give you back the $200 if the flash stopped working in 24 hours, or if there would be a fight to get that back?