I demonstrate how to remove/clear BIOS supervisor password from lenovo thinkpad laptops. I have tested this method repeatedly to clear supervisor password of my personal thinkpad W520 and W510. I have been using these laptop since, with absolutely no problem.
Theoretically, this method should work most of the Lenovo laptops. All you need to do is to find the location of EEPROM chip on your laptop (You can google it !).
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