i am favourite mind in computer science but also i am work hard in mechanical. So i can take computer software developer or mtech mechanical engineering
You should the one where your interest is.
You will automatically work hard where your interest is more. I you like studying computer science then simply go for CSE.If you have done B.tech in Mechanical engineering then better continue with M.tech in Mechanical engineering because that will benefit you most as you have already gave 4 years to that and starting new thing will create difficulties for you in future.
Good Luck

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