HHHEELLPPP .....a dead w800 to its previous glory and be thanked.

HI

my SEw800 just died for no reason. tried several batteries and chargers but same results. now i have to pull the battery out and then back in and when i press the power button only the first white screen comes up and then goes away leaving the phone totally paralysed. wont even respond to anything unless i repeat the battery procedure.
i dont usually kill phones i just play around with them unfortunately this one died on me for no reason. promise i didnt even mess around with anything this time. its a vodafone network unlocked version but i dont know the firmware type as the fone is not even showing up on setool.

would really appreciate if someone can shed some light on why this happened and what can be done to rectify it.

cheers
arch.