It seems people who have tried, cannot locate the jumper (check this thread: Write protection jumper on an Asus CX1700CK)
I have the same model as you (Asus CX1700) and ended up buying the debugging cable/circuit board on Ebay and unlocking the firmware that way. The process of unlocking the firmware with this cable (they call it a SuzyQ cable, idk why) is considerably more involved then simply shorting a jumper.
I’m available to help if you end up trying it yourself.
I had success after much persistence in unlocking the firmware, flashing with the Mrchromebox (UEFI) Full ROM, and installing Debian linux and Windows 11 on the machine (I ended up ditching Windows but wanted to install as a PoC, turns out the touchpad was non-working in Windows).
Here’s the Ebay link (as far as I know this is the only place you can buy a prefabricated Chromebook debugging circuit board, otherwise you’d have to breadboard the entire circuit yourself): GSC Debug Board (aka "Chromebook Debug Cable" / "SuzyQ", for Cr50 / Ti50) | eBay