Latitude 7370 battery light flashing orange, laptop not using the battery

The battery light on my Latitude 7370 started to flash in orange and the laptop is not using the battery. It does not start when the AC is not plugged, and shuts down immediately after the AC is unplugged. However, the Dell online diagnostic test for battery passes it as working OK (the test for motherboards also passes). In BIOS, I can see the battery as 100% charged; however it also says "Health: Communication Error". A week ago the battery still had enough charge for up to 5 hours of office work. I have tried to unplug the battery, start the laptop without it, and then plug the battery back. I have also tried unplugging and plugging back the CMOS battery. Neither of these helped at all. I have been using the laptop with WD15. The behavior persists on 2 different WD15 units as well as on the default AC charger.