Battery suddenly not detected -- but working

[bar_foo]

After waking my laptop up my laptop this morning I noticed that it was charged to 100%, which is unusual since power is managed by the BIOS and it normally charges to 75-79% to extend battery life. But then when I unplugged it reported that the battery was at 0%. Running the battery check in HP Hardware Diagnostics returned an error, and Support Assistant reports no battery present. On rebooting there's a BIOS-level warning that the battery is not charged (error 601), and I have to press Enter to start. And the UEFI Hardware Diagnostics produce the same result.

Yet oddly the machine is working fine on battery, even though it thinks no battery is present. I writing this writing now on battery power, even though Windows is reporting 0% remaining. So it seems like this is a software issue at some level, since the battery is charging and delivering power. And when it's plugged in Windows always reports that the battery is fully charged to 100%.

I've tried resetting the BIOS to factory defaults, reinstalling the BIOS power management update. Any other ideas?

Note: This battery is fairly new, it was replaced by HP because the original one had started swelling. 

[bar_foo]

More info: here's the start of the output from powercfg /batteryreport:

Battery Report

[bar_foo · Accepted solution]

Further update--a simple fix, in case anyone else encounters this issue: following a tip on another site, I shut the machine down, unplugged it, and rebooted while holding down the power button. It flashed the warning about the low battery, then after about 10 seconds shut down. After that it restarted normally and the battery is detected properly, with everything reported to Windows and the diagnostic app!