Lenovo W540 won't enter BIOS
Solution 1:
Why doing a Shut Down and Power On again can't get you into BIOS?
Windows 8.x doesn't really shut down the laptop completely, but puts it into hibernation state. This is called "hybrid shutdown", and was invented to speedup subsequent Windows startup. The F2 prompt on startup, only appears from a true cold boot.
How to get into BIOS in Win8.x?
Restart the computer. Restart ignores hybrid shutdown so the computer does an "actual" restart.
Hold the shift key while pressing Shut Down. This forces the system to do a true shutdown.
Now if you plan on entering BIOS for quite a few times, you can disable Hybrid Shutdown.
Go to Power Options>Choose what closing the lid does. Click Change Settings that are currently unavailable then uncheck Turn on Fast Startup.
You will be able to enter the BIOS in subsequent startups. The downside to this is, of course, you won't bootup as fast as if Fast Startup were enabled.
Sources here and here.