Comment 35 for bug 710738

@Dave, please also try acpi_listen and also check dmesg for any messages about unknown keys or scan codes or anything like that. There's also a tool named input-events that's more of a firehose than keymap, so it might show something that keymap doesn't. You can pass it only the number, so if you passed input/event3 to keymap you would run

  sudo input-events 3

Note that it will exit after about 5 seconds of no key events; you can make this longer with the -t option.