I had the same issue on a new Lenovo Thinkpad x220. I had always used "sudo halt" to shut down the system and discovered that it actually halts the system instead of powering it off. I think this behavior probably changed in recent Ubuntu releases, because in earlier versions the system powered off.
"shutdown -h now" and "halt -p" works, "halt" without "-p" only halts the system and does not power it off.
I had the same issue on a new Lenovo Thinkpad x220. I had always used "sudo halt" to shut down the system and discovered that it actually halts the system instead of powering it off. I think this behavior probably changed in recent Ubuntu releases, because in earlier versions the system powered off.
"shutdown -h now" and "halt -p" works, "halt" without "-p" only halts the system and does not power it off.