I have broken my HTC One (M8)'s display (and probably more) while attempting to replace the battery, and I'm selling it via eBay for parts. How do I attempt a full Nandroid backup with TWRP and then wipe the device securely, blindly? I have no screen whatsoever in the device, as the original one is broken. I had TWRP installed, as I mentioned. Is this possible via adb or fastboot? They seem to be working. I have S-Off and can get to the bootloader via commands.