Can you tell us about the battery?
Having problems with the umi z like many other, can you tell us if the risks that the battery swells is very present?
Were the tests more rigorous?
Battery in my Z didn't give any type of troubles so maybe you are just unlucky.
Another thing is that Crystal is not in my hand and is to fresh to be giving you any type of answer. I know that since Umidigi Z1 battery is modified.