k750i a little help please

Hi firstly let me say its a very nice site you got here , its my first post :)
Allthough i am not a noobie in pcs flashing etc i am a real noobie in flashing mobiles :)
So here is the problem , i have a k750i and when i open it it shows the sony ericsson logo then it restarts with white screen . A technician told me its the software but he cant fix it cause sony doesnt support anymore this model :/
So i am pretty sure that flashing the phone will make it work , but i am completely lost as in which firmware shall i install and what i should do first , i have the usb cable etc . A little help will be appreciated :)