My N80 recently got its flex/ribbon cable damaged (the one that connects the display with the body) so whenever I slide up, the screen goes blank.
I handed it over to the Nokia Care center and they inspected the unit. The warranty seal was broken (don't ask) but I convinced them that it did not tamper with it and they agreed.
They discovered that the flex was broken internal and it needed replacing.
They gave me a 6610i service phone to use.
I will keep you posted on updates....