I also have the "plugged in, not charging" problem with my Novotech NSPIRE C15B.
Unfortunately this would not have anything to do with which OS is running on the unit.
There are many forums stating that this is a common issue when upgrading to Windows 10, and I only started getting the error after doing so. I doubt that it's a coincidence that mine, gavrob's and many other's laptops have failed in the same way at the same time due to battery or motherboard failure.
I have tested my battery in a friend's NSPIRE, and it works fine. My motherboard has already been replaced once so unless Novotech has a particularly bad supply of motherboards, I don't think it is that.
...so I'm convinced this is indeed a problem with the OS and the drivers used to manage hardware.
The standard fix for this in other forums is to uninstall and reinstall the ACPI battery driver, which hasn't worked for me. My BIOS version is 616, but I also can't do the suggested update because of the
Power state in not safe for BIOS update. (Please check AC & Battery status.)
issue. Is there a new version of the BIOS update that doesn't have this error, or one that I can use to manually flash it?
Many thanks in advance.