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Sorry to here about your lightning damage. Might be time to review your renters/ homeowners policy for coverage
Consider having a licensed electrician check your entire property for damage to appliances like your HVAC, refrigerator, outlets, wires ....... 
I've had lightning strike a rain gutter downspout on a home before & the amount of damage can add up;
licensed electrician inspection adds peace of mind & is a requirement for most insurance claims
Was the PC & network connection protected from surges? How was it protected?
I've seen a PC get zapped through the unprotected network cable, even though PC was connected to a UPS
Digital meters are usually too slow to pickup quick changes, so analog meters can be better for troubleshooting
I'm not sure if the PSU is toast; though it sure sounds like it. Your test lead contact quality when testing (or lack of) can make an impact at low voltages
Place a small load on your PSU -- think fans or AIO & test again, also test any removable drive
Remove MB from case to test.... place on cardboard or other nonconductive surface & inspect MB closely with a good light ..... a damaged USB, drive ... can all stop a MB from working ..... the naked bench test is the best way: MB, CPU & cooler, 1-RAM at a time.... does it boot, unplug & add GPU - then test, next test add mouse & KB ck your PC case for sign of arcing ... the peripherals could be damaged FAQ
How do I test my power supply? FAQ
What are the voltage tolerances of each of my power supply's rails? ATX standards specify that power supplies have a +/- 5% maximum variance tolerance on each rail. For each rail, the voltages should be in between:
5 VDC+4.75 V to +5.25 V
−5 VDC–4.50 V to –5.50 V
+12 VDC+11.40 V to +12.60 V
−12 VDC–10.8 V to –13.2 V
+3.3 VDC+3.135 V to +3.465 V
+5 VSB+4.75 V to +5.25 V