Hello, I want to ask if some body knows what is wrong with  stat stop and it doesn't work even though the battery has been changed and is new. Thank you.

If you are a 1.0 Ecoboost rejoice! Your belts will last longer👍

The owners handbook says:

Limitations of Use

Manual and automatic transmission, the engine may not stop under certain conditions, for example:

• Low engine operating temperature.
• To maintain the interior climate.
• The battery charge level is low.
• The outside temperature is too low or too high.
• Opening the driver door when in motion.
• The heated windshield is on.
• During regeneration of the gas particulate filter.

Automatic transmission only:

• When the driver seatbelt is unfastened.
• The steering angle is greater than 90 degrees.
• Transmission is in sport (S) or manual (M).

Manual and automatic transmission, the engine may restart under certain conditions, for example:

• To maintain the interior climate, for example air conditioning.
• The battery charge level is low.
• The heated windshield is turned on.
• Your vehicle starts to roll downhill in neutral (N).

Automatic transmission only:

• When the driver seatbelt is unfastened.
• The driver door is opened when in drive (D).
• Transmission is shifted to sport (S) or manual (M).

 

Also have a quick search of the forum for hundreds of posts on the topic:

https://www.fordownersclub.com/search/?q=stop start&quick=1&search_and_or=and&search_in=titles&sortby=relevancy