I’ve just realised I can control my Panasonic Viera Plasma (ST50) with an API. It has commands for all the remote buttons I need except power on. The network interface is unavailable when in standby, there is no option for this in the network menu, unlike newer models.
This is disappointing as this is the last function I need to be able to perform to rid myself entirely of infra-red remote control.
So, short of disassembling the TV and connecting an (isolated) ESP GPIO across the power button, do you have any other ideas on how the TV could be powered on?