Ive never dealt with bud rot before but Botrytis is one of the most commen "bud rot" and if the stems arnt turning white with black dots/patchy areas then its not that. To me, it looks like you underwatered it and it needs more water from the heat, Cannabis grows in 68-88 F weather. your temps are too hot, so you really should spoil it with water. Good luck, hose her down and pray for a turn around, most likely will impede the growth of more bud.

p.s.

Your plant is showing signs of dehydration. Let the flood out. then soak her with a gallon of ph correct water and Nutes... (im an indoor guy, but a gallon of water seems logical)