Yes, you are eligible for BTech in Computer Science Engineering (CSE) after completing a diploma in Mechanical Engineering after 10th standard, but through a specific admission process called lateral entry.

Many universities and institutes offer lateral entry admissions for BTech programs. This allows diploma holders to enter the second year of the BTech program, saving them time compared to starting fresh.

The eligibility criteria for lateral entry vary across universities, but generally, they require a diploma in a relevant field (like Engineering) with a minimum percentage of marks.

While your diploma is in Mechanical Engineering, it's still considered an engineering discipline. This makes you eligible to apply for lateral entry into BTech CSE programs at some universities.

I hope it helps!