Problem Huawei P9 phone downloads instantly.


Good evening,

I hope I posted in the right category. My wife has a Huawei P9Grey and for a few days it has been charging instantly. That is, it has 80% battery and then out of the blue it is completely discharged....
Initially I said it was a software problem and gave it a general reset. The problem persists.
I analyzed it and saw that the moment the camera opens, the phone restarts.
I went to the settings, the battery section and there is no anomaly, something that consumes excessively. Besides, I noticed that the remaining time of use has enormous fluctuations, like it approximates to me that there are 17 hours and 30 minutes left, then in a second it tells me that there are 18:12 minutes left, then it decreases and so on.
I wonder if the battery is to blame or is it a problem with a consumer like the processor or others.

Thank you in advance