Why did Huawei mate9pro become a blackboard after upgrading the HarmonyOS system?

This is because Huawei mate9pro mobile phone enters dark mode.

Closing method: 1 On the phone settings page, open the display and brightness settings. 2 On the display and brightness setting page, turn on the dark mode option. 3 On the page of dark mode, just click the close timer/all-day switch.

Huawei Mate9Pro is a brand-new product of Huawei Mate9 series. The 5.5-inch nano-scale double curved surface screen has a dazzling effect, and the seamless connection between the glass touch panel and the metal shell is realized in industrial design. The front fingerprint is unlocked. Huawei Mate9Pro is Huawei's flagship model.