I have no particular knowledge of Samuel but have done some research on several generations of Mordecai Andrews.
Mordecai I c1715-49 Brought into revive moribund independent church in Petticoat St, London as a 'young man', presumably from Bocking. Expanded congregation so much they took over bigger premises in Artillery Row. Wife Sarah, children Mordecai II, Mary and Hannah.
Mordecai II 22/12/1738 - before 1820. Became independent minister of Great Coggeshall in immediate succession to Henry Peyto (can anyone tell me more about him?), perhaps around 1770. Married Elizabeth (probably Rutt) as children were Mordecai III, George Rutt, John Rutt, Edward, Charlotte, Charles, Eliza, Harriet, Frederick.
Mordecai III 1780-1820. wife Hannah Litchfield, son Samuel who might be yours, though born Bocking. Record of death says son of late Rev Mordecai Andrews. Which of Samuel's sons had Mordecai as second name?
Hope this helps
Mike