3rd gen Stick Up Camera - intermittent issues with live view etc.

Hi. I bought three 3rd gen stick up cameras for outdoor use. Two work fine but the third keeps failing to show the live view and record events, only very occasionally working. The wifi strength is fine on this camera. I've tried moving it to the locations of the other two cameras that work fine, and it doesn't work properly there either. I've also tried doing a factory reset and it hasn't helped. Does anyone have any ideas as to what's wrong? It looks like it's faulty, so I went on the online chat to ask about the replacement procedure for a faulty item, but frustratingly I was just told I'd have to phone up and go through troubleshooting first. This seems unnecessary as I've already done it all and have two identical cameras that are working fine. Thanks.