Strange, are You sure that You haven't explicitly enabled R&D mode, before?

On my device, enabling force-power-key flag doesn't result in any other symptom of R&D (other than wrench key in boot screen), i.e. no keyboard flickering on activity, and definitely no diodes behind keyboard lit, when screen isn't slided out.

I can't comment on it much, as it's my first 1st hand experience with R&D flags or mode at all (!) - never had need for using it. Maybe someone more experienced with R&D could explain it?

/Estel