Sony Ericsson T68i, z600, k600

Hallo to everybody. I'm Nicola, an italian electronic engineer. I'm not interested in repair phones for work, but often I used Sony Ericsson phones which I solved or improved formatting with firmwares found here, in Topsony site. I make my last upgrade about three years ago at my k600. I always used USB sync station "DSS" with semctool: I used several versions of semctool because I found that last version number isn't always the best solution for all phones. I noticed that USB1.1 is better than 2.0 (It crashes less), and with T68i I nearly lost my phone, but I found a method to recover it after a bad upgrade: you have to start upgrade without battery, ad insert it later. But i made this al lot of time ago, so i don't remember well what are the correct times to do so.
Now I'll try to upgrade a P1i, perhaps I'll solve some trobles it has with return and photo keys.
Thank you for all!