It looks like the larger NON electrolytic cap might have shorted. (it ain't there no more!!!) WOW!!
OR
The "lamp change" switch was making poor contact, and over heated the board and surrounding components.
This looks like a NON softstart wall switch.
The newer softstart wall switches have the processor in a different location, a daughterboard (AGC circuit), and two 10 ohm resistors in series rather than the one 22 ohm resistor.
(top picture is old style wall sw., bottom is new softstart)
Note the two 1/2 watt resistors tied together (extreme right in picture), and the processor is near the top and horizontal.
My picture of the new wall switch I have modified for the neutral wire connection (grey wire next to the larger blue cap).
The larger blue cap is part of the power supply and the smaller blue cap is part of the PLC coupling network from the 120Khz transformer.