HTC one m9 factory reset problem I need to do a factory reset on my HTC one M9. just for clarification, i have not rooted the phone ever. I'm trying to do a factory reset through the phone setting and once i do the reset it brings me to the bootloader. I'm not sure what to do from there. i try to boot it into recovery mode but it says "this build is only for development purposes only"

any help?
You can try this-- (for Hard Factory Reset)

1.Remove SD card and SIM card. Switch of your phone.

2.Press and hold volume down key along with power button, release power button when vibrates.

3.Navigate to reboot to bootloader with volume keys and select with power button.

4.Then select BOOT TO RECOVERY MODE.

5.Then select wipe data/factory reset.

6.Then Yes – delete all user data.

But as you mentioned that it says "this build is only for development purposes only". Then you can try resetting with setting menu.

The detailed process to reset M9 by setting menu and Hard Reset is given here

If none of the method works then you may need to visit the service center.