@stourleyk 

Hi,  
1. You can edit this thread on a different browser or device and check if you can key in the model number Tapo C425.

2. Does the original power adapter and cord power the Tapo C425, but you can't turn it on by pressing the power button for three seconds? If so, try a different power outlet and a different power adapter (if you have one), then press and hold the reset button for 10 seconds to factory reset the camera. 

If the same phenomenon persists, contact your retailer or the local support team to check if the camera is under warranty.

Best Regards