update issues

[pappahog45]

hi, i have an unlocked UK htc m9, i tried the OTA nougat update and its failed....repeatedly. now my phone says its modified, cant factory reset or get in any of teh boot loader options (other than to select recovery or download and it fails to load) any ideas on how to get it back to factory..that a chimp can do mind, im not the most savvy on flashing and stuff.. :-X