thank you guy so much for the repair guide that worked just perfectly – and unfortunately still didn't fix the problem. I changed the battery, the phone started and worked fine, until the battery got low. When I tried to charge it, it wouldn't work. Maybe the battery I replaced wasn't even broken, maybe it was something else. I will never find out since I measured charged of the old battery and it was dead; but maybe it died sometime in the six month I left the phone in some drawer.
Anyways: Idead about what to do now, or maybe if there just isn't anything left to to will be really apprecciated.