That message probably turns on if the battery measures below a certain voltage with the engine not running, probably if below 12.0 volts. Normal engine-off battery voltage is 12.6 volts or above. So the test to do is make sure the battery voltage is 12.6 volts or above and see if that message comes on. If it is, there’s something wrong with the gadget that does the check. Whatever does that check must use a precision voltage regulator, and that device may have failed.
The basic battery alternator voltage check is pretty easy to do also. Just requires a voltmeter connected to the battery posts: Before the first start of the day the battery should measure about 12.6 volts. Immediately after starting the engine, it should measure 13.5-15.5 volts. What do you get?