With respect to transformer stations exploding, "the grid" is exactly like your house, only at a meta level. There are electrical lines going through it, and shunted through key nodes. Like your fuse box. If you plug your computer, your TV, coffee maker and Stove into one single electrical socket you know what will happen. Everyone knows what will happen. Either the safety breaker blows, or the socket catches fire.
An electrical grid functions under the same principles. In the United States, we have three separate grids, (necessitated by the physical speed of light and the need for Texas to Special) That are supported by primary power stations all over America and Canada. In the event of an Emergency (i.e, a power station shutting down) the other power stations within the grid or in an adjacent grid can pick up the slack. And this is done in much the same way you throw a circuit breaker in your house. They are already running, but the power is not flowing until the breaker is engaged and the electrons can flow. This is done automatically by computer in America which is why you almost never see random black outs that are the norm in the third world who do not have redundancy built into the system or computers running emergency algorithms.
So what happens with a grid like Venezuelas where 80% of their power is reliant on a single location? Well if something happens at that location the system hard crashes. There is no redundancy. Worse, after it crashes it cannot be restarted without power flowing through the system. The US has three separate grids for this reason. If one of the three goes down it can rely on the other two to jump start the system that crashed, or even better, mitigate the spread of the blackout by throwing emergency breakers to isolate the emergency and rerouting power through the hard line to the separate grids. Which is what we did in 2003.
Venezuela does not have a diffusion of power supply. Its self contained with no links to any other power grids. So when their primary power supply went down, their auxillary plants blew as well. Much like how your own circuit breaker would blow if you plugged 6 items into the same socket. After those plants hard crashed Maduro, in his infinite wisdom demanded that his state owned power company get the power back on RIGHT FUCKING NOW!. So they tried to do just that. But due to the blackout, Everybody in Venezuela had turned all their electrical shit on. Their fridges, computers, air conditioners, coffee makers, lights, etc etc etc. So as the system was attempted to be brought back online ALL AT ONCE, the power surge got fed through a few key nodes and immediately exceeded their tolerance levels for the amount of electrons flowing and KABOOM. This also helps to crash the system AGAIN, only with dramatic twitter videos this time.