Hello.
I have bought Garmin Oregon 750T (HWID 2512, official firmware v6.0 installed) yesterday. I have activated Birds Eye Imagery subscription with BaseCamp (It shows that subscription is active till 04.07.2023) and downloaded and sent to Oregon Birds Eye Satellite Imagery of a small area to test. Everything worked correctly. Today I have loaded to BirdsEye folder on Oregon's main storage (not sd card) some custom jnx files. And now when Oregon starts, I see Garmin logo, after few seconds the display turns off (just when it shows on the bottom of the screen text "Oregon 750T, Copyright 2016, Garmin Ltd"). When screen is turned off I can hear beep signal when pushing user key. After next few seconds Oregon turns off.
1. I have tried master reset - without sd card inserted I can't even reach prompt "Erase all user data?" - it just turn off. With sd card inserted after selecting "erase", Oregon turns off.
2. After connecting to PC, computer don't recognize that any device is connected.
3. I have also tried Forced USB Mass Storage Mode. I hear pc sound that same device is connected (but it's not available as storage in My Computer) and after few seconds, the sound that device is disconnected (the device remains connected even longer If I hold power button longer). I use original Garmin cable provided with Oregon 750T.
4. During preforming Forced USB Mass Storage Mode, I have also checked WebUpdater, it recognizes Oregon 750T correctly during short period when my PC recognizes that some device is connected.
5. I have also tried to perform firmware update writing gupdate.gcd file to Garmin folder on sd-cards. Unfortunately, there is no newer FW than 6.0 available and of course nothing happened after Oregon was turned on again.
Any solution? Please.

Update:
I have saved patched firmware v6.0 to sd card. Now during boot I reach prompt "New software found. Continue installation?" And then screen is turning off and after few seconds Oregon is off. Maybe is it power supply problem? When I connect Oregon equipped with original Garmin batteries to power socket there is no information that device is charging. It stays turned off. I'm charging now Eneloop batteries in 3rd party charger and will try to boot again with fully charged Eneloop batteries inside Oregon.

Update 06.07.2022:
Fully charged batteries didn't solve my problem. I have also observed that pushing user button during boot I can get to mark a waypoint screen and even menu for about 1-2 second just before Oregon shuts down.

Update 06.07.2022 v.2:
Problem solved:
I was able to bringback mass storage mode using garmin cure v3. 2 seconds of connection was enough to send rescue firmware. I have deleted all jnx files and using cure flashed normal firmware. Now Oregon boot correctly.

The conclusion is to not use internal Garmin storage to write new files (maps, gpxs etc.). I have read it on this forum but it was after I made wrong decision.
Best Regards

Topic is closed.