I have 3 Lenovo E540 Thinkpads. 1 of them works fine but the other 2 will not boot unless I remove battery and power cord and unplug the bios battery for a while which clears the bios. But once I completely shut it down and try to restart I get nothing. I tried to update the bios but when it goes to reboot it does nothing and then I have to remove all power and unplug bios battery for a while. All 3 have clean installs of Windows 10. I got all 3 of these used so I don't know the history on them.