Recently a client called saying their fairly new E540 wouldn't turn on or respond at all. The red light that makes up the "i" in ThinkPad would light up but that was the extent of the functionality.
I tried removing the battery and booting off but no dice. The computer was totally unresponsive. It turns out there is an issue with Lenovo for Small Business software that causes this.
To fix it, remove the BIOS battery - this is located under the compartment to the left in this photo:
Stick the battery back in and give it the berries. The laptop should boot and complain about the time and date. Set those and start the laptop. Log in, go to Uninstall Programs and ditch the Lenovo for Small Business. Once that's done, it's probably a good idea to update the BIOS. Try not to screw that up by killing power or anything mid upgrade. The recovery process is incredibly annoying and not guaranteed to work.
A reboot and you should be right to go. Enjoy.