VIXIA HF G50 won't start up--two of them!

[qaddict]

I have several Canon Vixia G50 camcorders that I've been using for the past few years in my small videography business. One day last week, one of the cameras suddenly wouldn't turn on. It had been working perfectly 15 minutes before, and then nothing. That was weird enough, but a few hours later the exact same thing happened to a SECOND camera.

We tried several different batteries and 2 different AC adapters and nothing. They won't turn on while plugged in or with any batteries that are full. 

How could the exact same thing happen to two different cameras on the same day?? Does anyone have any insight or can think of anything to try??

Thank you for any help!

[qaddict]

OP popping in here to add that a THIRD camera just died out of nowhere as well! This time I put in an SD card right before it wouldn't turn out. Is there any way that a corrupt/faulty SD card can cause the cameras to just die?? I've never heard of anything like that before, but something had to have caused 3 working cameras to die within a few days of each other and it's possible the same SD card was used in all?