Project-Help /Arduino Nano 33 IOT

Hello, I'm using arduino nano 33 iot and I just need to use accelerometer and it's enough to get it with simple accelerometer code. I have uploaded the wifinina library and after uploading the simplewebserverwifi code to my arduino, I have successfully combined the codes. I want to buy my power supply from the powerbank and when I remove the cable, it gives the error of not finding the port, I can't use it as iot. Where could I have gone wrong?