Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['7815', '475', '6153', '7831', 'Z', '2751', '63', '4255', '8069', '6689', 'x', '2315']

7815, 475, 6153, 7831, 26, 2751, 63, 4255, 8069, 6689, 24, 2315