The nicks are in the trailing edges of the propeller. I'm not sure a spinning prop could get nicked on the back side, I would expect the nicks on the leading edge??
I didn't know why, but with the tab 3 I would get a lost signal, RTH message every time I tried it. I tried flying from several different locations but still couldn't get more than a couple hundred feet out.
Are you using the same tablet on the bad flights or have you tried swapping that around also? I had the same problem using my Samsung Tab 3 (not tab 3 lite) but it works fine with my Galaxy 5S and my Insignia 7.85.