Traduciendo paso 5
Very the Keyboard connectors are clean and no pins are damaged before verifying connected properly.
Remove the Keyboard to inspect and assure the Keyboard connectors are clean and not damaged. See pgs 79-81, or as noted in the PDF reader as pgs 85-87, of the "thinkpad t40 t40p t41 t41p t42 t42p Maintenance Manual" for more details if needed. This manual is found in the Attached Documents section at the end of this Guide.
Proceed to the next steps to inspect, clean and reconnect the memory module under the keyboard, palm rest, antenna, fan, LCD screen and CMOS connections before reconnecting the keyboard, otherwise reconnect the keyboard connection and install the keyboard.