The original Electro was a male.
But he's still alive, correct?
I haven't even seen the character, but I was guessing it was a female.
You are correct, he is alive. I assume they will explain the switch later on, but who knows. I am sure it is just one more move in Marvel's plans for an entirely female universe. Maybe it will be written really well and most of us will like it, but I doubt it.
There were hundreds of Electros in the first arc in Web-Warriors. They had universe jumping devices, so this is possible explanation they may use, one still was out in the wild.