The first thing needed for a repercussion of Mechanical engineer working in software Industry during B school interview is being “Honest”. You should try your best to present your answers in a manner such that even the last option would seem like your first choice.
If you are inclined towards Mechanical engineering, you should follow that. You can even choose to go to any software firm if you need quick money or want to be in a convenient job so that you can prepare for the MBA exams.
At last, you should make sure that you showcase positivity and confidence in the interviews without any regrets.