Can't update my Nuvi 2597LMT, won't go into update mode

I am trying to update my Garmin Nuvi 2597LMT, but it refuses to go into update mode when I plug it into my PC.

It just boots normally and then gives the error that the cable cannot be used for traffic information. Nothing I have tried seems to make it go into update mode, and Garmin Express can't see it if it's not in update mode. I know the cable is fine because not only did I try a second cable with the same results, but I had just used that cable to update an older Nuvi 2595LMT with no issues. I also have updated this 2597 in the past with no problems before, but it has been a while since I last used it.

 

I just installed Garmin Express on this PC, so it should be the latest.

I tried rebooting, also tried an entirely different computer.

Also tried several USB sockets.

The same cable was able to update my 2595 no problem, but the 2597 can't tell it's being plugged into a computer.

I also did try setting the 2597 to Mass Storage mode, it still made no difference. The GPS didn't detect it was plugged into a computer and it did not show up as a drive in my computer, didn't see anything listed in Logical Disk Manager or Device Manager either.

Just to make absolutely sure it's not the cable or the PC I tried that same cable and that older 2595 in another PC, this time a Laptop that does not even have Windows installed, much less Garmin Express, but is running Linux, and the 2595 still functioned as it should where instead of the main menu it displayed a yellow icon of it being plugged into a PC, it even recognized when it was unplugged by turning the icon grey. Tried again on that same laptop with the 2597, and same thing, it just boots up normally as if I plugged it into power with that "I agree" screen then the warning about the cable not being suitable for traffic before going to the main menu instead of recognizing it's plugged into a PC and going into "update mode" or MTP mode or whatever that mode where you can update it is called. The 2597 itself that seems to not recognize it's being plugged into a PC, even forcing MTP in that developer menu didn't seem to make any difference.

 

Well, this isn't what I was expecting:

https://i.imgur.com/R4h4a2S.jpg

I admit, I was fully expecting it to just say "Power Cable" like you said and that the USB port was broken considering it keeps acting as if it is only getting USB power and not data, but instead when I plugged in the USB cable it said "Generic Serial" for a second and then switched to "Serial Host".

Strangely, when I attempted this with a charger instead of a PC (Specifically, the USB port on my UPS that the PC is plugged into), it STILL said Serial Host instead of Power Cable.

Also even stranger, ever since I entered that debug screen for the first time the "This cable cannot be used for traffic" error message no longer appears even through multiple shutdowns and reboots.

This is making less and less sense to me now.

 

Yeah, I had set it to Mass Storage mode, I also tried setting it back to the default MTP setting to see if it would make any difference and it did not.

 

I actually tried two different cables. In fact, I don't completely remember, but I think it didn't even come with a data USB cable, just a USB to Car adapter charger. One of the cables is the one that other 2595 I mentioned game with, and the other is a modern gold plated Monoprice cable.

With no USB cable it hovers around 0.63-0.64. With a cable it hovers around 0.65-0.67, mostly around 0.66. When I unplug the cable while on this screen it doesn't go back down to 63/64 nor does it stop saying "Serial Host".