Computers & IT (Non-Engg)

Do Masters (MCA, MBA, M.Sc). It will be a good option and why do you want to do Bachelor again, that too BCA?

It is not necessary to have a B.Tech degree. You also complete some certificate courses, you may complete any web designing course in which you are interested, after getting a certificate, you can apply in a company and easily get a job. (B.Tech degree gives you knowledge in rhetorical form, but certificate gives the practical knowledge which is more demanding in IT field).
Thank you.

Mainframe consists many courses like:
COBOL: COBOL Developer's salary: INR 3,00000-7,00000.
DB2: Salary of a Database Administrator (DBA) is $82,323.
JCL/VSAM: The average pay for a Mainframe Systems Programmer is Rs. 593613 annually.
CICS: CICS Systems Programmer's Salary. A CICS Systems Programmer earns an average salary of $78,987 per year.
IMS DB/DC: IMS DB/DC Developer makes an average of $86K, ranging from $60K to $114K.

You can check for Qwikmind.com. They offer all the online courses with highly experienced trainers and the fee is also less and reviews are also good even though they started the company recently, they are doing a good job.
http://www.qwikmind.com/big-data-data-science-analytics
List of course they provide:
Digital marketing
Big data Hadoop
Project Management
Salesforce
Mainframe
Mobile Development
Cloud Computing
Big data and analytics.

I don't think there is much difference. In IT sector, knowledge is given preference over the degree course. Whether you do BE or MCA, if you don't have the required knowledge, you won't get a job.