Diploma

National Institute of Computer Arts offers only Diploma course which can be pursued after 10+2. So, have a look on the courses awarded and decide on the Diploma which you wish to pursue.
Link: https://www.shiksha.com/college/national-institute-of-computer-arts-dadar-west-mumbai-25514

Yes, you are eligible for lateral entry B.Tech after completion of Diploma. You have to appear for LEET examination to get a good college.

Interested candidates can apply online with required information and admission is based on the marks obtained in 10th.
Check out the link below for details:
https://www.shiksha.com/university/mewar-university-rajasthan-other-30805/admission#admission

Hello Parikshith, It's indeed heartening to know that you are interested in higher studies. I would advise strongly that you go for AME rather than Aeronautical Engineering branch. This is so since opportunities in later are rather limited and you would be competing with mechanical engineers for many jobs. On the other hand, opportunities for AME are increasing with each passing year as can be seen by reports of each commercial airlines announcing procurement of large number of aircraft.

You need to tell about the qualifications you have at present first.

If you want get admission in b.tech mechanical so you can easily apply in any college of b.tech by showing your diploma mark-sheet.
If you have your diploma mark-sheet, then it doesn't matter whether you have completed your 12th or not.

Which stream have you graduated in?

What kind of scar are you telling about?