Tried my first FIM and it didnt go well.....

So I had 2 plants I tyres to experiment with tryed topping them. It stunted both plants badly and wilted one and when the fan quit and temps peaked she died.
The other one is making a come back but has been stunted badly
as you can see

I just pinched off the middle part like all the stuff I read said to do. The plants were a month and a bit old when I did that to it.

This is how it looks 2 weeks later

So is it my tech that's off? Did I wait too long to top?
Can you guys give me some pointers