Possible that the
surge had resulted in the SMPS- switch mode power supply - giving a higher output before it would have corrected but had resulted in the
failure of some component.
Remove the panel if you can start the work armed with a multimeter, the mains power being put off. wear insulated slippers while probing the circuits specially when the power is switched for
voltage checks.
first of all check the main power unit :click for tips on
SMPS
If there was no fault noticed visually then
check the processor controller section specially the voltage to the processor. If the +5 volt is missing check the regulator or the feed.
If there is power then check if the mP activates the HT circuit, if not the main board
had errors to be looked into
with a trace of the working voltages, look specially for
charred or damaged components.