There is a built in Function Test that you can run to test certain areas of your HTC One to make sure the hardware is working properly. You can use this to troubleshoot those areas listed to see if there are any issues with the device. You can test everything at once or just choose certain areas that you might think that are having certain issues. So for those who might think they are having issues with the hardware you might run the test and see if the test pass. If any of them do not I would recommend that you email HTC support to make them aware and see what actions they recommend.
You can get to the HTC Function test by opening your phone dialer and using this code. *#*#3424#*#*
Here a list of areas that the HTC Function Test checks.
Audio Test
Bluetooth Test
Charger Test
G-Senor Test
LED Test
Line Drawing Test
Camera Test
Wifi Test
Backlight Test
Button Test
Flashlight Test
Headset Test
Light-Sensor Test
P-Sensor Test
Vibrator Test
You can get to the HTC Function test by opening your phone dialer and using this code. *#*#3424#*#*
Here a list of areas that the HTC Function Test checks.
Audio Test
Bluetooth Test
Charger Test
G-Senor Test
LED Test
Line Drawing Test
Camera Test
Wifi Test
Backlight Test
Button Test
Flashlight Test
Headset Test
Light-Sensor Test
P-Sensor Test
Vibrator Test