ASUS UX330UA battery not detected

[AB1234CD]

My ASUS UX330UA previously did a "battery unknown" warning, and now the laptop only works when plugged in. When on, it shows battery as 79%, but will immediately lose power upon being plugged out. I've tried updating the BIOS, but no such luck.

 

[birne]

This might work.

shut laptop down.
remove battery and power cord.
press power button for 20-30 sec.
insert battery.
plug in power cord.
power on.

If this does nothing then the battery probably is dead and has to be replaced.

 

[AB1234CD]

This might work.

shut laptop down.
remove battery and power cord.
press power button for 20-30 sec.
insert battery.
plug in power cord.
power on.

If this does nothing then the battery probably is dead and has to be replaced.

Battery cannot be removed. It's an Ultrabook.

And just as a PS, it did this last week too, but it fixed itself within 5 minutes, and the laptop wouldn't die when I removed the plug. It would just say battery unknown remaining.