This worked for me. It’s slow because the camera app keeps popping up, but keep trying. It helps to have a friend around with a IPhone so they can show you what button to aim for in the brief seconds you are not interrupted by the camera app. And also so you can refer to the these instructions or others.
Tell Siri to do a hard reset
Even if you think your phone is updated, check. Update if necessary.
Go to Settings>General>Transfer or Reset phone>Reset>Reset All Settings
It will ask you to confirm. (On that screen, it will assure you that you only be resetting your settings and not setting your phone to factory reset.)
Confirm.
If it doesn’t auto boot, reboot your phone.
When I rebooted the camera app was finally quiet.
(If you don’t know to do some of the instructions, for example the instruction reboot, just have a friend Google: reboot iPhone instructions and you will find the steps to do this.)
Good luck!