First post here: I have been reading this site for a long time and could not find the solution to a problem I just experienced (and solved) on my 4 years old OP-1.
In a matter of a couple of days, the "<" key got extremely sensitive, to the point that the weight of my finger touching the key would activate it. After contemplating ordering the iFixit replacement keyboard or sending my OP-1 back to TE, I decided to pop the key out, as described on the iFixit website, to have a look.
I found that under the key was a bit crusty... I remove the little scissor lift piece, cleaned the whole thing (by blowing in it) and put it back together: it works again! my theory is that some dirt got between the scissor lift and the rubber dome, shorting it.
I hope this can help anybody who gets in the same scary situation!
cheers!