well.. i can't :(

the Z550i has a design-failure...
when you close the phone the display always hits the microphone. and this Z550i already had a broken mic when i bought it. so i replaced it by myself. and because of that there's no warranty anymore... :(

well.. i think there's some hardware damage causing the flash-function not to work.
i don't know why but what else could that be except a hardware-failure..?!

i tried it on 3 different pcs.. always the same.. nothing happens.
and on all 3 pcs it works when i connect my W810 or my D750 @ W800.
so i guess the Z550 has some kind of hardware failure making it impossible to update the firmware or doing something else that needs the flash-interface..

if someone here has a suggestion what to do to fix that or has the same problems.. feel free to post a comment here..

i'm giving up for now.. =/