How to Remove the BIOS Password from an IBM ThinkPad 240

I bought a second-hand classic ThinkPad in great condition, but it had a BIOS password (supervisor password) set.

The supervisor password prompt lock screen.

The ThinkPad was in very good condition and barely used, so I decided to un-brick it. To retrieve the BIOS password, you will need to

Disassemble almost the complete notebook.
Build an EEPROM reader.
Connect the EEPROM reader to the EEPROM chip on the ThinkPad 240.
Dump the EEPROM content.
Extract the password from the dump.

For me, shorting EEPROM pins didn’t work, I had to dump the EEPROM and decode it. I followed the instructions provided here, which worked for me.

Disassembly and Locate the EEPROM

Use the ThinkPad hardware manual provided by IBM to disassemble the classic ThinkPad. Take great care to not break anything, the plastic is 20+ years old and became brittle. I use a hairdryer to heat up the plastic to reduce the risk of cracking.

On the 240 ThinkPad, the EEPROM is located on the bottom side of the main board, requiring complete disassembly. The EEPROM is located next to the NeoMagic video chip. The chip is relatively large, so it is not too difficult to solder a few wires to the chip.

You will need to solder a small and simple circuit that you can connect to the COM port of a debug PC. The circuit is not great, won’t work with all COM ports, but it is cheap and easy to build. If you only want to unbrick your machine and the alternative is to throw it away, by all means give it a try.

You only need three wires: ground (GND), serial clock (SCL) and serial data (SDA).

The recommendations are to connect the wires and to dump the EEPROM while the ThinkPad is running. To make this easier, I added some pin headers to the soldering wires to be able to easily connect them when the notebook is running.

Dumping the EEPROM

To read out the EEPROM, a service PC with a powered COM port is needed. USB-to-serial cables didn’t work for me. In the end, I used a ThinkPad X30 with a COM port, which worked well.

Install r24rf08.exe (the EEPROM dump software).

Assemble the ThinkPad 240 so that it can start. Make sure that the CPU fan is placed on top of the CPU. The EEPROM reader should be disconnected.
Start the 240, and wait for the password prompt to appear.
Connect the GND cable to your EEPROM reader.
Connect SDA and SCL.
Run the dump tool on the service notebook (e.g. in a PowerShell) r24rf08.exe dump.bin.
If you get an error message ERROR: Eeprom not available, your COM port is likely not powered (this may happen if you use a USB-to-serial cable). If everything worked well, it should look like this: