Hackaday covered the outage and some background:
And a commentator (‘Moebiusar’) supplies a video of the official version of events (in Spanish), and offers a precis:
…another Argentinian here. In this link: https://youtu.be/OYdAcLh31Og you can see the official version about the incident. It’s a ~three-hour-long (surprisingly technical for the place IMO) hearing that went on 2019/07/03. Long story short, they were doing some maintenance on one of the biggest transmission lines and “forgot” to update the Automatic Generator Disconnection parameters upstream. Later on, a common line fault (aggravated by human factor) led to a full blackout.
Another commentator offers a much shorter summary video, also in Spanish: