I would first reach out to Wyze: By phone: (206) 339-9646 Available Monday - Friday 5 am - 6 pm PT and Saturday 8 am - 4 pm PT
By your explanation, it sounds like you have physically removed power, waited for a bit and plugged it back in. If you did this and it did not work, plus you tried flashing the it back, then it might be a HW failure.
here is a link to another topic pertaining to the same issues:
Based on your description your cams are bricked and there’s nothing that can be done about it. Since the cams v3 have been released in November 2020 you are still under warranty. Go get the dead cams replaced ASAP (and hope that Wyze figure out how to resolve this issue otherwise be prepared to the thought of having all your cams being bricked by same time next year).