Dead key on A600

[Jope]

Yes.

If it's only that one key and not a column or row of keys, then reseating the keyboard's flat cable might not help a lot.

Wipe the rubber under the key with a piece of paper from your printer, until the rubber is no longer shiny.

Clean the dust off the membrane inside the keyboard.

[Jope]

If you want to make a mess, then why not. The problem with the graphite approach is, that it also wears out with use pretty quick.

Wiping with paper to refresh the rubber's surface, then making sure the plastic membrane is free of grease and dust will yield long lasting results.