Might have to spin this off somewhere, my fault for OT/flooding, but hey, wot's new?

All this is assuming your 255W IS the non-MTK HWID 0827. You can see it in GarminDevice.xml, look for "<PartNumber>006-Bxxxx-00</PartNumber>" to check that 'xxxx' is 0827. If it's 1091 you'll need the MTK firmware and you can't convert to US 465 or any Asian fw. You can also see it on the unit, press and hold the battery symbol near top RH corner of the main screen to reach hidden menu > Next > Start Test > More to see 'Inventory' page. Look at top 3 lines, second entry "Bxxxx-00".

So if you have the non-MTK chip, you can also get 0827 fw from
Code:
Please Login or Register to see the links
[To see how i found that, right-click on the page from your post's Garmin link above, choose 'view page source' or similar to open a new window then look for the GCD link near the top].

I much prefer to not use gcd files, even though they only present a slight risk of bricking. Several ways to do it with a gcd:
  • After connecting the nuvi to PC in MSM, drag nuvi2x5W_GCDFile__780.gcd onto WebUpdater.exe or it's shortcut icon and that will transfer it as gupdate.gcd to the Garmin folder; or
  • Rename nuvi2x5W_GCDFile__780.gcd to gupdate.gcd, hook up the nuvi in MSM then drop it into the unit's Garmin folder; or
  • Place gupdate.gcd on an SD card in Garmin folder [x:\Garmin\gupdate.gcd], turn nuvi off, insert card, turn nuvi on.

I prefer to use preboot. Make the gcd into an rgn file with RGN_Tool and name it 082701000780.rgn, drag it onto Updater.exe and flash in the usual way.
Or, you could look in the Tutorials ... it's all in there.

Three of my 255Ws are running SG/MY at present, versions 2.50, 2.80 and 3.00. If you want to try An asian conversion don't flash the full fw. Only make a hybrid fw, using the US boot.bin and keep the HWID as 0827.

PS: The only really worthwhile back up of a 2nd hand unit initially is of region 41 [for older unit like 2x5 use "rrgn,41,1:/41.bin"]. That's the commonly called 'NV backup': [Only registered and activated users can see links. ].

EDIT: Ok dude, ya got your own thread so knock y'self out. Prof Neil's wiki service is now live 24/7. Advice worth every dime! [All advice is free, no care taken and i can't even spell respuns ... err.. reponserbil ... ]