Quote Originally Posted by berin View Post
....... on the 61o I get "cannot authenticate maps"
You get the 'cannot authenticate' message on the M610 even though the maps are 'unlocked' due to fw protection called 'MSV'. Sure they work on the M600 but they don't pass the authentication test on the M610. That's because the M600 doesn't have MSV (Map Signature Verification) whereas the M610 does have that protection (albeit the 'weak' form).

If I understand correctly, the 610 doesn't have advanced protection (there is no gupdate.gcd file) .....
Yes it has protection, but it's the 'weak' form as stated above. Additionally, the absence of the GCD means absolutely nothing in regard to that. Most outdoor devices auto delete the GCD file after it's been invoked anyway.

... and so the unit can't be patched.
Wrong. It's firmware can indeed be patched with the Universal Firmware Patcher by big-bang. Join Masters Section if you want to know more.

Yet the maps still don't run. Do I need to make another change to the unlocked mao .img? If so what, and what tools do I need?
The 'other change' is to use ImgTool to change the map IMG's Code Page. I don't think you fully understood my comments in Post #6. You can use unicode maps without patching fw for M610 if you're prepared to mess around a little, read this: [Only registered and activated users can see links. ]. That's only applicable for devices with weak form of MSV such as your M610. It's a bit of a kludge but you did ask if there was another method apart from patching fw.