Only 50% chance that the symptoms was caused by a lightning strike because your cable box was powering on fine. Most of the cases when lightning strike near to your area, possible of multiple damaged to the electronic device not only to one particular appliances, most especially if they are plugged into the outlet. Also, fuse will blew because of excessive voltage.
I've suspected that the symptoms was only a co-incidence of lightning strike. If you can hear the clicking of the relay, this is only means that the standby power supply is working fine. However, this board has multiple output voltage feeding the other boards to function well. This kind of symptoms is a power supply related problem.
If you have necessary tools and test instrument and handy with electronics, you can troubleshoot this board to find the faulty parts like open fusible resistors, shorted transistors/IC's, leaky electrolytic capacitor, etc.
Another option is to replace the entire power supply board, this is more convenient if you are going to DIY because no soldering required. Try to find you board HERE
. Type the model no. of your unit to the search engine, available parts/board will be display.
Hope I helped you.
Have a nice day!
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