Yesterday I had the "firmware upgrade" button available and working (begins to download upgrade components etc) but my internet was playing up, so I tried again today and all of a sudden Kies was telling me "'GT-I9100T' does not support initialisation" (and upgrade component downloading window did not appear).
As suggested by Sparx, I checked my debugging setting. It was already unchecked, BUT I found that when I checked it, then unchecked it (the phone will prompt you to remove USB cable before you can toggle this option) it restored the "firmware upgrade" button.
Frustrations which remain:
The process began again but stopped half way through, telling me that "phone battery is low, charge phone battery" (phone was plugged in via USB and charging already from computer). When I clicked OK, the process aborted and I am back at the Kies screen without a "firmware upgrade" button again (so will have to toggle the debugging option again - annoying, but faster than rebooting computer and/or phone).
Kies doesn't tell you the download size - I have dialup
broadband with a small bandwidth allowance and cannot afford to be
downloading excessive amounts. It would be really helpful if we
could discover the sizes of these upgrade downloads.
Kies re-downloads firmware update process files (the ones before it
starts downloading the actual upgrade files) each time I attempt to
upgrade firmware - even if this was done 1 minute ago. I would think
Samsung would have the programming prowess by now to cache these
files rather than re-download them (for me, this also relates to
I hope this helps others.