Built-in Camera Not Working and Blinking

Hi guys,

MacBook Pro (Retina, 13-inch, Early 2015), MacOS Catalina 10.15.4 (19E266).

A few days ago I downloaded Zoom the video-conference app. The camera was not working in it but I did not pay much attention because it happened before - the camera was blinking green for quite a long time, and then usually worked in other apps. This time it didn't though.

After 10+ hours of reading different threads, articles and FAQs I pretty much did everything there is to do to make camera work - from sudo killall VDCAssistant to reset SMC - until I remembered that I forgot to uninstall Zoom. Once I did, camera started working like magic instantly in all apps.

Of course, if I were smarter, this would be the moment to not deal with Zoom any more, but I just had to download it again to see what the problem was. And this time the camera worked. But just for one video-session. When I quit Zoom, it stopped working again in all apps.

I tried to uninstall Zoom but this time it didn't help. What helped - was installing it again, and I had a video-conference. After that, the camera stopped working again.

I tried the uninstall-reinstall sequence a few more times, along with uninstalling some other apps like Skype. Tried killall and reseting SMC. But nothing seems to be working.

When I open the monitor, there is no activity related to the camera - no VDCAssistant where it's supposed to be, and nothing in the plugins folder.

Therefore, the issue is fully software-related and it's not about hardware. I tried running in safemode: while in the regular mode, FaceTime, for example, says that there is no signal incoming, in safemode it doesn't find the camera at all.

I also have to clarify that I updated my OS to Catalina 10.15.4 two day ago after the problem started (thought it would help), so it is not the latest system update. I also contacted Zoom support, haven't heard from them yet, but judging by their response to other similar queries, they will say that since the issue prevails in all apps, this is not their problem.

I would really appreciate any advice on this very urgently, as we are all stuck on this quarantine and still have to work from home, basically meaning that 90% of my working time is video conferences. The camera doesn't work anywhere - facetime, imovie, skype, Facebook messenger, Hangouts, Zoom, even Preview which I used to add signatures via camera.

Thank you in advice!