SE W910i - v diff problem to all on internet

right the phone in question is a 15 month old w910i, in december last year it went in for repair due to several faults (software etc and no screen when slide was open) they basically just replaced the top half of the phone, software issue was still a minor problem but i have a new and very different problem

i lent my phone to a friend for a month untill he got a new phone because his old one was destroyed, anyway he tells me that the phone just cut out working whilst he was using it, it had recently been in his dads rucksack and was in a dry enviroment.

the phone will not charge now, its not the battery because phone would norm work if plugged into charger w/o battery which it doesnt, its not the charger - used 2 diff chargers, both work on other se's

when plugging the charger in i get a blinking red light on the left soft key (just above the button with green phone icon) and it continually flash's until i press the power button - then the phone has no action whatsoever. also the slide has become very stiff. does any1 have any idea wat has happened? and is there any easy solution? (tried charging overnight)

i have also dismantled the phone to the point where if i went any furthur i would be voiding warrenty, iv got to the slide mechanism and i cant figure it out :(

please help:(