My low battery light and occasional beep says it's time to replace the battery. Before I can do that I need to know how to open the battery compartment. I had VZ Tech support on the phone coaching me but there is no obvious way to open the battery compartment that is visible to me. The compartment is alleged reserve hinged which makes sense but I can't even get a fingernail the door to open it. Any suggestions. (By the way the reserve power for the hard wired phone worked during Irene and the Snow outages.