I find A139 unstable. One day it works fine, the next day it restarts several times while driving for no apparent reason. I have to have my smartphone connected to Wi-Fi at all time to know if the dashcam is working because I already had a situations where it turning off by itself and even one time before my (new) car was hit in the parking lot and the A139 didn't work at this time.
I'm tired of connecting via Wi-Fi to see if it works. I had previously learned the painfull lesson not to buy Chinese and I made the mistake again. Seeing "made in China" on the box, I should have sent it back, but I didn't do it, thinking that good appearance implies a good quality.