What are the chances of changing one's branch from production to CSE in BIT Mesra?

BIT Mesra branch change procedure does not depend on the branch you are changing from. It depends on several other factors like 

• Number of vacant seats in each branch (maximum 4-5)
• CGPA of people applying for branch change. The higher your CGPA, the more your preference will be considered. 

Irrespective of whichever branch you belong to, your chances of changing your branch to CAE are the same as other students. All you need to do is score excellently in the 1st and 2nd semesters. You should at least target an 8.9 and above to be among the top 3-4 students. Scoring such a high CGPA is indeed very challenging. 

However, you will spend a lot of time on branch change and end up missing a lot of fun activities so consider it only if you are serious about branch change.