When mine died it was really fast, over night. They wilted and twisted and that was it, I have a pic here. This is what it looked like a few hours after I added ph down.
Here is mine, it's about 3 weeks, i gave a little too much nutes on the first feed, but she's fine now. I had those tips curled down too, lowered the dosage and she seems better.
Pic 5 looks a little like too much nutes maybe...but shifting ph does cause problems... I killed a plant doing that the last round, what is your humidity?
You can top where ever you want, I topped the main stem then topped the two that grew off, then LST then let it grow, then topped all and any thing I could ^^ working with around 30-35 tops now..on my original amnesia
It's still pretty cool though, they have packs of pre rolls that looks like a pack of cigs, a menu to choose from , a counter full of edibles and daily specials..like that episode of Weeds when Doug gets a medical card and shows Nancy the collective.