GPSrChive Discussion Forum

I recently purchased Garmin Montana 680t. Almost brand new with original screen protector on it. I suspect that it was used couple of times at most.
Wonderful device in excellent condition.

What shocked me was the firmware version - it was 3.70. Checked in Settings -> About, Garmin Express and GarminDevice.xml - 3.70 everywhere.

Inside GPSr\Garmin\GarminDevice.xml file, there was:
Garmin Express claimed that I was up to date, except TimeZone maps which I have updated.

Then I have decided to downgrade it to "original" 3.50 firmware (GUPDATE.GCD), by putting the file to GPSr\Garmin folder and temporary changing SoftwareVersion sting inside GarminDevice.xml to lower version (ie. 340).

It downgraded and it works. Now I have 3.50, but I cannot return to 3.70 now. When I go to Garmin Express it claims that I have already "latest" firmware version.

But the version 3.70 was surely more recent. When I was on 3.70, during boot the message Copyright 2021 was displayed. Now on 3.50 the message Copyright 2019 is displayed instead.

Now I don't know if 3.70 had any improvements and fixes ? Or is it similar situation like with GPSMAP 65, where 4.50 and 4.60 are the same firmware versions (except some copyright adjustments) ?

What may be important is that my device displayed BRP Logo* when booting instead of Garmin Logo. So I suspect that it was an addition to BRP Ski-doo Can-am vehicle due to Garmin and BRP partnership.
Otherwise it is 1:1 identical to original Garmin Montana 680t.

*) BTW, I finally restored Garmin boot logo using RGN Tool and logo.bin file from original Garmin Montana.

That is quite fascinating!

I might assume that 3.70 was, as you say, for BRP Can-Am devices, and may only differ in logos displayed, etc. But without one of each device side by side, we cannot be 100% certain!

I absolutely loved my 680t, but after using more current devices, I find it to be far too sluggish to use any more. I am spoiled by the newer processors!

GPSrChive wrote: Sat Jan 24, 2026 1:38 amBut without one of each device side by side, we cannot be 100% certain!

Yes, we cannot be. I do not understand why they updated firmware just to replace boot logo (splash screen) ?
Montana firmware files (GUPDATE.GCD) doesn't contain logo section, so flashing them leaves logo intact. In other words: there is no need to change firmware version just to change logo, because they aren't related.
Also branded firmware typically isn't compatible with unbranded one (ie. different HWID / PartNumber in GarminDevice.xml), so you cannot just flash original GUPDATE.GCD on branded device.

In the past, I had two branded Garmin receivers.

The first one was Garmin nuvi 760 with Volvo brand.
It only had changed boot logo (from Garmin to Volvo) and nothing else. Everything else was 1:1 identical to unbranded one.
Then I just flashed original Garmin boot logo using RGN file and it was 100% original since then (indistinguishable).

The second one one was also Garmin nuvi 760 with Mercedes Benz brand.
It was nightmare. Not only boot logo was changed, but also different HWID, different (outdated) firmware version and some branding inside gmaprom.img (yes, no maps was there but some branded Mercedes sub-menus).
I have removed gmaprom.img, and then tried to restore original up-to-date firmware using RGN file (instead of GCD file), but the device bricked.
Then I have created hybrid RGN file with boot.bin extracted from original Mercedes GUPDATE.GCD and the rest extracted from original Garmin GUPDATE.GCD.
After changing HWID of such hybrid RGN firmware file, it worked. And such forcefully unbranded device worked flawlessly since them with full functionality, without any failure.

The Montana 680t case described in this topic, looks like above Volvo case not like Mercedes case. It seems that only boot logo was changed and nothing else (no more branding except logo).
So I am just curious what changes firmware 3.70 from year 2021 contains ? Maybe, I will just ask Garmin.

GPSrChive wrote: Sat Jan 24, 2026 1:38 amI absolutely loved my 680t, but after using more current devices, I find it to be far too sluggish to use any more. I am spoiled by the newer processors!

I bought it extremely cheaply (for 1/3 price of new GPSMAP 65s) just out of curiosity.
But what I can say with TalkyToaster maps it works petty decently. I just reduced map details (in settings) to reduce unnecessary details when zoomed out to 1.2km or above.
It surely works faster than eTrex 32x (still sold) and with similar speed to Oregon 700.

The only case, when it is sluggish is when satellite imagery is switched on and zoom level is 80m or above. But in such scenario, mu other Garmin devices are sluggish too.

Of course, it is not the device with the most recent bells and whistles. But is is also the device which works with gloves, in rain, etc (as in movie) whereas other touchscreen devices don't.