Downloaded the non installer version of map 950.6544 and extracted the map on to the root of the device, deleted the old map 890.4234 and patched the new map with FA option 2. The .meta.dct is created for the new map.
Disconnected the device and started it. The device starts and an empty map shows with no routes or street names. The device then restarts and again the same map with no routes or street names show up, not able to access any menus and then the device restarts in a loop .....

post the current ttgo.bif.

Sorry for the delayed response, was out all day yesterday.
Though you strictly told me not to do anything on my own, I had to try this and test my luck as I had to go out and needed the TT very badly; but, with all due respect - the good news is that I sorted the issue by formatting and installing a fresh copy of "9.510 power up" navcore and map "United_Kingdom_and_Republic_of_Ireland_950_6544"
Thanks a ton to you for the quick responses and troubleshooting tips, Downunder for his Navcores and the entire team
I promise I'll try and help the noobs in resolving their issues when I can (though my knowledge is limited but, I understand the agony & pain in bricking/experimenting with the TT )
I now have an issue with the computer voice "Kate" not working, I'll read the posts and try & figure out; if you can, please point me in the direction
This place rocks
Please mark this issue as resolved now

[TomTomGo]
DeviceName=TomTom XL
DeviceVersionHW=ONE XL (v9)
DeviceSerialNumber=XXXXXXXXXXXX
DeviceUniqueID=XXXXX XXXXX
RamDiskVersion=20130404
BootLoaderVersion=55136
LinuxVersion=842337
ApplicationVersionVersionNumber=9510
ApplicationVersion=1234792.1
UserLanguage=English UK
UserName=XXXXXXX
LastConnectionTime=Never
GPSFirmwareVersion=2.16.201 77382
BuiltInColorScheme0=Belgica
BuiltInColorScheme1=Brittanica
BuiltInColorScheme2=America
BuiltInColorScheme3=Germanica
BuiltInColorScheme4=Australia
BuiltInColorScheme5=Deuteranopia
BuiltInColorScheme6=Greys
BuiltInColorScheme7=Antarctica
BuiltInColorScheme8=Africa
BuiltInColorScheme9=Astra
BuiltInColorScheme10=Asia
BuiltInColorScheme11=Brasilia
BuiltInColorScheme12=Concordia
BuiltInColorScheme13=NewAnglia
CurrentColorSchemeBuiltIn=11
CurrentVoiceInfo=Kate
CurrentMap=United_Kingdom_and_Republic_of_Ireland_950_6544
CurrentMapVersion=950.6544

Thanx for the update. Enjoy!!