How do you revive a dead FM37 mp4 player?

I have a dead FM37 mp4 player. As in dead I mean completely unresponsive. It will not turn on at all, even if plugged in my computer or USB wall charger. When plugging in my PC it doesn't get recognized. It was working fine until about 6 months ago. I had been using it until the battery was completely dead, then tried to recharge it but it would not start. I have tried holding on the power on slider when charging and in normal mode, tried holding reset and even the "connect pins on chip with tweezers" trick. I have opened the device and the battery is full and firmly connected.

any ideas?