Logitech MX 3200 wireless keyboard

I have a Logitech keyboard/mouse combo that's about four-years-old. A couple days ago, the warning light flashed telling me the keyboard's batteries needed changing. I swapped out four AAs and pressed the red reset button on the bottom, but the keyboard didn't work. I tried four other new batteries and checked the USB connections at both ends, but no dice. The mouse continues to work fine. I am using a wired USB keyboard, but want my Logitech back. Is there anything else I can do?

JP