You have to have adb/fastboot on your computer. Boot your phone into bootloader. Hook it up to the computer and make sure the phone says 'fastboot usb'. Browse to where you have adb installed on the computer and open up a command prompt there. At the prompt, type in 'fastboot erase cache'. Then type in 'fastboot reboot-bootloader'. When your phone comes back up, try and get into recovery again.
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Phone: AT&T HTC One (M7)
ROMS: AT&T Sense 6 M7 Developer Edition
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