It's why I write to avoid running on battery and keep that AC connected as the battery has a finite life span. 18 months would be a very early failure unless the battery was used daily.
If the laptop suffered any drops or falls then it's usually not the battery but a trip to the service center for repair ($$$).
You can try the old reset first (no data loss!) Turn it off, remove AC, remove battery then press, hold the power button for 60 seconds. Release, slip in the battery, apply AC and then re-test.
There are other causes such as accepting drivers from Microsoft but most have learned to not do that.
I have my laptop for one and a half year, and yesterday I noticed, that
my battery is not charging. Laptop runs ok when it's plugged, but
without it I can't start it. And when I unplug it, it will immediately
shutdown. BIOS is v2.40 = upgraded. I didn't do anything unusual with
it. Maybe the new battery is the solution, but still I think it's
another problem because my battery used to last for approx. 45 min! Also
I checked the battery, and it's not physically damaged (no corrosion
etc.) = looks and fits good as new. Reinstalling the battery in Device Manager didn't work. Oh, and when I look on the tray icon
of the battery it says "AC plugged, is not charging battery, consider
battery replacement, 0% charged", battery on the trey image is empty and
red crossed. Also when the laptop is of and plugged battery charging LED
indicator doesn't light. It lights for approx. 2 seconds after I turn on the computer.
Does anyone know a solution to this problem?