The subscriber you dialed is power off. Was it hacked?

This may just mean that the other party's mobile phone is turned off or dead, or can't answer the phone for a certain period of time. If you keep calling this reminder number, you may be blacklisted by the other party. If you want to determine whether you have been hacked, you can try to contact each other in other ways, such as sending SMS or WeChat. If you can't contact each other in other ways, you may be blacked out.