It appears that the usb cable has been inserted upside down. The usb port maybe possibly damaged.
Start the ps4, and once it has booted, pull the power plug. Now remove all usb cables. Restart the ps4. It will give ypu a warning about needing to rebuild index. Let it.
Now take a look at the usb port, amd cable. Notice on the cable there is a diagram of a USB connection. That diagram should alwaus be facing up when placed into the port. It is possible ypur sister has forced the cable in upside down. You should be able to connect the cable, and the controller now.
Thank you so much for your response, as should be noted, the USB has been inserted correctly each time. When plugging USB in, it saids "to many usb devices connected" and now it won't let me reconnect my controller and I'm stuck onscreen of the ps4