That depends on the country of origin and the cause. If this happened in the US it would require an extensive filing with NERC and most likely several public hearings before regulators and lawmakers. Then laws would be written to attempt to prevent the incident in the future. For example, see the repercussions from the 2003 Northeast Blackout [0].

If this was caused by state actors, in part or whole, then I would expect most hearings and reports about it to be less public, and occur behind closed doors.

[0] https://en.m.wikipedia.org/wiki/Northeast_blackout_of_2003

Extremely in-depth? Yes. Public? No.