Hello and thank you for your question. I look forward to assisting you today. How old is it and have you had any problems with it before?
Try this to see if you can correct the problem. Take the back off by using a fingernail, or something thin like a small flat blade screw driver to pop off the plastic quilted cover. Gently remove the battery. This is should be a large, thin rectangular object. The battery is attached to the reader with a small cable, possibly emerging from the bottom right hand corner of the battery. Grasp the small white plug at the end of the cable and gently wiggle it while pulling, to detach it from the reader. Once you have unplugged the battery, wait a few seconds and plug it in again, making sure you feel a click. If you don’t feel the click, try again, otherwise the plug may not be properly seated. Place the battery back in its compartment, ensuring you loop the wires under the tab at the bottom of the battery housing, so they don’t get pinched. Snap the back of the reader back into place and try powering it up.