Toshiba Equium A110-233: keyboard malfunction

The H key stopped working on a Toshiba Equium A110-233 - an obsolete but until now reliable laptop. This was a problem as H was in the power-on password. Notes on the Equium:

• It uses a Fn key to emulate a numeric keypad but it won't emit Alt code based characters.
• It recognises USB keyboards at boot time/in the BIOS.
  • The Advent K112 wired USB keyboard was the cheapest I could find at short notice
  .