Left for the weekend and came home to a problem

Ok guys I hope I can find the answer to my problem here. I left Friday afternoon and came home just now, Monday afternoon to my plants looking like this. As you can see one still looks fine but the other three are having a problem. Do you guys know what it is? Some curled leaves, and some yellowing/oranging. Actually just noticed the one that doesn't have any color change is starting to have a little leaf curl to it. I watered them with plain water right before I left with no nutrients. Could they have grown too close to the light while I was gone? Or dried out too much or could it be my PH? I haven't really fooled with the PH cuz I've read some people say they can be just fine without messing with it and my General Organics says you don't have to adjust with it and have seen a lot of people use it without adjusting. Here are the pictures, let me know what you think.

Looks like you had your lights too close. Hold your hand under your light at plant level, if its too hot for your hand, too hot for your lady's.

Check your ph next water and definitely give them a feed, mate. Mild nutrient solution if any at all. See how they go after that, and if they're too close to the light they would still be too close to it?

I moved the light up, they weren't too close when I left but grew up and I had just switched to my 400 Watt HPS from my 400 Watt MH. Hopefully they were just too close and recover soon, I'm gonna feed them again tonight probably.

Looks like heat stress. They'll let you know soon if it isn't

Good luck bro

They all came back to looking great except for this one. Does that still look like heat I've learned my room has to be open or it gets too hot so i open it as soon as i get up. So it heats up to hotter than i want evwry morning but then I'm able to bring it back down for the rest of the day. They all seem to be handling it just fine besides this one purple kush here