What you can do is force restart the phone using the hardware keys, and only hardware keys (because the software is not playing along anymore!). Under this method, the OnePlus 7 Pro will force shutdown and restart automatically, and when it does, the ‘not responding’ problem will be fixed.

Drain the battery completely. This means using your device until it powers down by its own and the battery level reads 0%. Charge the phone until it reaches 100%. Be sure to use original charging

oneplus 7 pro restart problem