In 2012 I had a Canon 5D mark II with which I shot my thesis film. It worked fine – but there was a strange clicking sound we all heard both while filming, and during playback when we reviewed recorded video footage. I took a problematic video clip, put it on a disc to show the issue, and brought it to Hunt’s Photo in Cambridge, MA. I told the manager the problem and, instead of even looking at the camera, let alone researching the issue, he said I could just 'get a new camera.'
"I can just...get a new camera?" I asked.
"Yeah," he said. And that was the extent of his explanation.
Except it wasn’t new, it was refurbished. This ‘new’-not-new camera drained batteries and spontaneously shut off for no reason. I sent it to Canon and had them inspect it, and they sent the camera back, stating that ‘nothing seems to be wrong.’
But, of course, something was wrong, and the problem persisted.
Do you know what the original clicking sound was? The camera lens’ image stabilizer was on – and all I had to do was shut it OFF. No one told me until I had a crappy, defective device, and I happened to mention the problem to a filmmaker acquaintance I knew.
So, I sold the Canon-cleared camera to B&H – after all, Canon had just inspected it and confirmed that ‘nothing was wrong.’ I then went back to using my 9-year-old Olympus E-410 SLR. There isn't a video feature, but it takes great photos, doesn't drain the battery, and it fits easily in my bag.
Of course, you should always research the products you're using, especially new technology, so you don't run into issues like this. However, it's also reasonable that a store specializing in camera technology with certified staff members might help you research the problem, too.