I need please some more data regarding this case:
What was the melanin meter read of this patient's chest?
What Hz you have used in the fast mode?
Have you performed a test and if yes how long you have waited after the test to see skin reaction?
Did the patient complained during the treatment that its too hot for him?
It is written in our user guide that its recommended to cool the skin down with cold packs, I recommends to read the user guide as well.
In dark skin patients you will get a hair clearance even without a perifolicular edema/erythema.
Is this guy is one of neoasia team, if not can you check with him how his skin looks like today?
I recommends to apply an Aloe Vera gel in cases like that.