Hi navlem,
I still wonder why you have (Sg/My) gupdate.gcd file in your Taiwan unit.
Did you buy it from Garmin dealer?
Why did you have swv 2.50 at first ? (2.50 is swv of US firmware)
Is it possible that ., the shop converted US unit to other region ?

Could you please go into inventory page to check boot HWID ?
Normally it should be the real hwid of the unit.