The reason why the computer's black screen button shows inpowersavemodepressanykey is that the monitor can't detect the display signal of the host computer and enters the standby state. You can try the following methods:

1. First, after disconnecting the power supply, plug and unplug the data cable of the monitor (remove the two fixing screws).

2. Check the graphics card: If the host can run and the display is normal, it may be that the graphics card is in poor contact or damaged and needs to be turned off and plugged in again. If it still doesn't work, you need a new graphics card.