I think that the Chrome OS 70 update broke my Acer Chromebook 14 CB3-431-C5FM

Kumicho

Chromebook just updated to OS 70, and suddenly both my Chromebook 14 as well as my sister's (who I assume updated to 70 sometime in the past two weeks) have had the camera stop working.  In Hangouts I just get "no camera on this device" or something similar, and when I try to open the Camera app it just goes to a black screen (and no camera light).  Anyone else having this problem?  It's almost certainly an OS issue, since the OS just came out and is affecting both my sister's as well as mine (yes, I got her the same computer as I have so it's easier to run tech support for her).

Anyone else have this problem?  Unfortunately I tried the Beta channel first before reverting, and now it only switches back and forth between 70 and 71 as opposed to actually reverting to an older, previous version.  Or any thoughts on what I could try?  Have restarted, powerwashed, powerwashed with reverting back, Beta.  Haven't tried Dev channel yet.

wis

Back up personal data. Sync browser. Reinstall.

Pssst3

Save whatever you need from the Downloads folder to a temporary folder on Drive.
If you have an external SD card installed, remove it.

Install the Chromebook Recovery Utility.
Take 8GB or 16GB USB stick and plug it in. 
Run the Chromebook Recovery Utility.  (It will ask for your model number.)
Follow the directions.
When the process completes, you will need to reenter your Gmail credentials and your router password.  The recovered Chromebook will have an old, perhaps very old, version of Chrome OS.  Don't try to do anything with it yet, let it run for at least an hour.  If it attempts to update, let it.  After an hour check for updates through the Settings/About Chrome OS.  If it doesn't find an update, wait and hour and check again.