Before you do ANYTHING with it (before you root, before you flash a recovery etc...) Follow these directions courtesy of cschmitt Found Here This will ensure we get all the partitions
I have pasted the steps below. This will help the community out greatly!
I have a windows command script that uses adb to dump and pull every partition from a One, excluding cache (meaningless) and userdata (to large).
He would need adb and fastboot on his computer, no need for S-off, since we are only reading partitions.
Generally the process would be:
Enable USB Developer options and USB debugging on phone.
Connect phone to usb, install drivers from zip folder if prompted.
Copy SuperSU-v1.41.zip to sd card.
Reboot into bootloader. (Power off, hold power on an vol-down.)
Open command prompt into \htconedump folder.
Unlock bootloader, fastboot oem unlock should do it.
Reboot back into bootloader (via hboot menu.)
From command prompt:
fastboot erase cache
fastboot boot openrecovery-twrp-22.214.171.124-m7.img (Take note we are not flashing recovery, just booting into it so we can root. If you flash the recovery we will not be able to get the stock GE recovery pulled)
Once TWRP boots, flash SuperSU-v1.41.zip via TWRP to root device.
Reboot back into system.
Run pullmmc01-37.cmd command script from a windows command prompt.
Zip up the dump directory containing all of the mmcblk0p??.bin files.
I've packaged everything up into a zip file containing ADB, fastboot, HTC drivers, superuser.zip, TWRP image, and the pullmmc01-37.cmd command script.
Also make sure to take note of your CID in the bootloader and also report that in this thread. You can get this by running fastboot getvar all while in the bootloader. The MID and the CID will be listed. Please make note of both.
I would advise anyone doing it that they do it without fully setting up the phone because once you unlock the bootloader it will wipe your data. So boot into android and just skip through the whole set up process because you'll just have to do it again after you unlock the bootloader
EDIT: Got this info from the Dump thread on Android Central. Just need to confirm it's correct with someone who has the device