HTC one m8 wont turn on after camera replacement

My camera was malfunctioning, and so i replaced it. Unfortunately the device wont turn on, when i charge it, it only shows an orange blinking LED, and the charge icon. Even after hours of charging it shows no sign of charging the battery..... I have tried various methods (hold power button + volume) But so far none have worked.... What can i do? I dont even know if its the battery who is broken, could it be something else? Like the motherboard for instance? Please help :)