My Amigo PD600C PDA doesn't seem to be working, and I think the problem might be the battery. I need a 3.7 volt 1550 mAh (or higher mAh) Li-Ion battery. There are 4 contacts on the front (each about 1/4 inch wide 1/8 inch apart in the middle). The dimensions of the battery are 2 inches x 1.5 inches x 7/16 inches. The contacts are along the long side. Thanks.