I recently ran Lenovo's update tool on a Windows 7 Home Premium T430, where one of the updates was a BIOS update.
The update tool downloaded and installed most of the routine updates and then prompted me letting me know I was about to update the BIOS so I should save work, close applications, etc. It also gave me the option to "change model number" or "update BIOS." The default selection was update BIOS, so I chose that, closed my applications, etc, and continued.
A command line window popped up for a second, and then the computer seemed to shut down, with a "Shutting down..." screen and everything, but now it appears to be in some sort of sleep/hibernate/broken state. It's unclear to me whether or not the BIOS update ever occurred or was attempted and failed or anything. The power button is slowly blinking like normal sleep, but won't wake up with a key press or mouse click. I'm afraid to press the power button to try and wake it in case something is still happening with the BIOS and I kill it by powering it off.
Should I just try the power button and see if it leaps back to life? Is there some back-door recovery that I should be trying to use? Should I wait? It's been hanging there about 30 minutes now, and a BIOS update shouldn't take that long.
In this case, the T430 BIOS update actually doesn't happen until after the system reboots. It does not sound like the system fully rebooted so it seems likely in this situation that the BIOS update never happened. You should be safe to power the system off and turn it back on.
Check what happens if the power button is depressed - if the system beeps and the power LED continues to blink slowly, uplug the power cord and remove the battery, then reinsert the battery and power up your system.