After I put the metal bottom covers on I take a small thin file and lightly scuff the edge where my finger always sits. This allows me to sort of turn or ensure the button is turned as I start to
vape. On a delrin cover I heat my knife and make three small grooves.
A combination of doing this and getting used to my REO resolved my inadvertent locking problems.
It is habit now to be sure the button is unlocked as I bring up to my mouth to
vape.
EDIT: I live in a dry climate and my hands stay dry so the grooves and rough edges are needed so my finger doesn't just slide around the button.