ok. last night I discovered my plant got burned, p...

It's nute burn. You are using 5 gallon of soil, there's no need to feed so early, heck 3 gallon of soil lasts me 7 weeks with no added nutes. So stop feeding, only feed in soil once you start seeing the first symptoms of deficiencies. Meanwhile feed water only.

Autoflowers don't use the same amount of nutrients as a photoperiod seed. Actually use far less. That's why it's recommended to start nutrients at 1/8 strength of manufacturer recommendation. Then bump up to 1/3 max. I would do a flush with plains pH water. Resume feeding at 1/4 and go from there.

Hi @Steve420! You can consider removing the most affected parts, this will improve your airflow and light penetration. You can also use seaweed kelp extract to help her recover from that stress (BioBizz, AdvancedNutrients, PlatiniumNutrients, Terralba.. have some seaweed products). Happy growing! 👊

I would recommend a product with seaweed extract to help your plant in this stressful situation. For example BioBizz Alg-a-mic. "Stress-free, happy plants generally produce larger fruits. And Alg·A·Mic™️ comes to the rescue if they’ve suffered from overfeeding, deficiencies, diseases or fluctuations in temperature. It also ensures green leaves, by stimulating chlorophyll absorption." You could use a controller for your heater to make sure it stops heating when gaining a specified temperature to stop overheating your tent. Make sure the heated air isnt directly blowing on your plants.