Diagnosing a Potential Software Issue

Hi, new to refurbishing PS4s but not new to electronic maintenance. I have a PS4 Pro that was given to me by a friend for repair, it evidently had been having issues with freezing and not launching games after being plugged in during a thunderstorm (was unsure if relevant). They tried to boot it into safe mode and now it is stuck there, with the only option available being Mode 7.

Attempting to use mode 7 with a USB containing the system software got nowhere, it would get to about 99% and then just hang, and hang, and hang without any change. Reformatting the HDD and then attempting to reinstall the PS4 software produced the same result, and when the hard drive is replaced with a functional hard drive from another PS4, it still boots into safe mode with the only option Mode 7.

Any ideas for what direction to take? Is this a software issue that can be easily corrected, or should it just be abandoned and sold for parts?