Project stops working when USB is unpluged


hi guys, finished first project, put in box etc , powered battery , mmm…it's not working.

when it's plugged usb works unplug stop's working properly.

the project rfid scanner relay, correct card , relay opens.

after power-up battery led's blink etc , first scan works after cards won't scan.

i have tried portable 5v usb battery, aa batteries etc…makes no difference.

any ideas guys?

what board?

post code.


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