Why is my Samsung galaxy j3 emerge restarting by itself after I restor

try the following

1. Charge your Samsung phone to 100% battery left and turn off the device.
2. Press down the “Volume-up”, “Power” and “Home” buttons to access Recovery mode.
3. Use the “Volume-up” and “Volume-down” buttons to choose the “wipe data/factory reset” option.
4. Again, select “wipe cache partition” using the “Volume-up” and “Volume-down” buttons.
5. Tap on the “Reboot System Now” option to reboot your phone
6. and then see if the phone still restarts itself.

should the above method not fix the problem then try the following

1. Go to Settings on your Samsung.
2. Find and click Software update/System updates.
3. Tap Download and install
4. After the update file is downloaded, just follow the on-screen instructions to install it on your phone.
5. After restarting, check if your Samsung phone is running normally and stop turning off then on.

I hope this helps you with your problem if the problem still persists then it can only be a hardware issue and you will have to take it into a repair shop and have it looked at.

please let me know of the outcome

thanks