(in addition to posting summary of these in the group spreadsheet dedicated to the topic) I recently published a longer form version of trail cameras failure symptoms, root causes and fixes on our blog.

See: https://winterberrywildlife.ouroneacrefarm.com/2021/06/30/how-some-trail-cameras-fail/ 

Failures covered include:

1. Stuck IR filter
2. Run-on triggering
3. Loss of focus
4. Early battery draining
5. Flash failure
6. No photos taken