If you lock your 2008-2010-era Thinkpad with a supervisor password and forget it, there is not much you can do. Unplugging the battery won’t help (although I have heard that supervisor password on some models can be removed this way) and getting Lenovo to fix it for you can be time-consuming, especially compared to how easy to service and how well documented these machines are.
This tutorial could work on other laptops, not only Thinkpads. I personally tested it on Thinkpad X200 and T400. The key to success is knowing which EEPROM and which pins on it to short. This tutorial however focuses on the correct sequence of actions to take.
I will try posting this to thinkwiki as well, but nobody responded to my registration request yet. I haven’t found this method documented properly anywhere else on the web, so I will post it on my blog at least.
When it’s there it will be somewhere at https://www.thinkwiki.org/wiki/Maintenance#Recovering_BIOS_passwords.
- Disassmble the laptop. Use the Lenovo’s epic Thinkpad maintenance manuals
- Prepare an environment on your desk, so that you can short the pins while having usable access to the display and the keyboard. This is especially cumbersome on a laptop like T400, which has the EEPROM chip on the bottom side of the motherboard
- Locate the EEPROM and the pins. See TODO Resources helpful in locationg the EEPROM
- Power on the laptop
- When the Thinkpad logo shows, use a conductive tool (a flathead screwdriver will do) to short the pins. Keep them shorted.
- Get into the BIOS by pressing F2
- It should get you into the BIOS without asking for any password. If it did not, you either broke the short or are doing something wrong.
- Now go to Security and disable Supervisor password by filling in an empty one. Do not enter another password. While it could work, it did not for me.
- Release the short
- Press F10 to save changes
- After rebooting, it should not ask for a password anymore
Resources helpful in locating the EEPROM
This website has the images for many laptops. If it ever goes down, use archive.org’s wayback machine.
Just replace t400 or x200 with your model, it apparently works for many laptops.
If something went wrong, feel free to write a comment or e-mail me at plantroon at plantroon dot com.