F[Only registered and activated users can see links. ] I'm giving you brief history about unit:
The unit freezed in 2012 (as per it's owner statement) during navigation and after restart it freeze on Loading map screen.
Unit HWID is 0827, onboard FW 6.40 - checked with G7toWin.
The unit could not be seen by computer after connecting through USB 2. I tried also the old trick - during initial startup (Garmin screen) switched off the unit and it goes to charging mode. Some old units can be seen from PC in this mode.
Hard reset is impossible as pressing lower right corner did not working (unit loading normally, in my case to Loading maps).
Preboot mode is possible through [Only registered and activated users can see links. ]. It is also possible to enter preboot mode by pressing spot over G of Garmin screen.
If I continue to press preboot spot for more than 30 seconds it goes to calibration mode, but it freezes on calibration screen.
On unit should be CNEU 2011.20 (as much as owner can recall).

What I did up to the moment:
Tried to load original FW 6.10, 7.40, 7.60 and 4.60. The updater.exe sees unit, process starts, them Software Missing appears, the firmware loading goes too fast and then info window appears: The Garmin device is not able to program ...If you continue to receive this message contact ....
Unit behaviour did not change.
Created Cure FW with [Only registered and activated users can see links. ]. Same procedure as above - no change in units behaviour.
With FW 6.40 (thanks again Neil) original and cure the procedure goes more smoothly, unit + updater.exe thinks more, but in the end of the day the result is the same.
As per Loly's advice tried to erase region 48 though SD card command. The unit did not see the SD.
I think that is all as info I can give.
[Only registered and activated users can see links. ] as I do not know how to modify boot.bin as *.rgn.
Neil - please explain what to do.

Guys, all we are aware that our units will not live forever, so soon or later we will lost them.
The unit is not mine, I know the owner barely, never seen him. I declared to the owner the unit is 99,99999999% dead.
But continue trying to heal the unit, is a matter of principle, gives me more good experience and valuable knowledge.
So if some of you have some idea, even crazy one - it is more than welcome.