i was looking on Se-NSE forums and i found these topics:
http://forums.se-nse.net/index.php?s...=6291&hl=w550i
http://forums.se-nse.net/index.php?s...=8035&hl=w550i
http://forums.se-nse.net/index.php?s...=6185&hl=w550i
http://forums.se-nse.net/index.php?s...=8305&hl=w550i
it seems like you'll have to bruteforce the phone, it is a long proces and the battery must be charged, (remove it from the phone replace it and charge it, even if apparently nothing happens the battery is charging). try those posibilities, i'll look after that DaVinci thing tomorow.