I can't get to the screen that will allow me to transfer a map from my PC to my TomTom XXL 550.

Jachens

And they say the device is obsolete and is longer supported!

justmebrowsing

Don't use TTHome, just copy/paste your map folder from your PC to your device which will be recognised as an external drive

Alternatively here's a workaround to get back to a version of TTHome that retains the old functionality:

1) Uninstall TTHome
2) Download last "good" version from http://download.tomtom.com/sweet/application/releases/v2_9_91_411_win.exe 3) Install it without running ie, uncheck the 'Run Home' tick box when installation completes
4) Using Windows Explorer, navigate to
C:\Program Files\TomTom HOME 2\xul (32 bit Windows)
or
C:\Program Files (x86)\TomTom HOME 2\xul (64 bit Windows)
and find application.ini file
5) Edit application.ini file (you might need admin privileges) and modify "Version=2.9.91.411" to "Version=2.9.99.999"
6) Run TTHome. It will believe it is running latest version 2.9.99.999 so will not try to update TTHome again but still allow you to Operate my GO/Manage my device etc

7) Please report back here if successful