Your question is not clear to us. I am answering based on the case, I have understood . See if you wish to do the BE in Mechatronics then you can obviously do that after the Diploma in EEE. But if you wish to do Diploma in EEE after BE in Mechatronics then you can do it based on your 10+2 or 10 score but the thing is the Diploma in EEE will not be of much use.

Now its your choice. If you wish to go for the BE in Mechatronics after Diploma in EEE then you can go through the later entry admission (if available in the college you want to study ) , where you will be provided admission to the BE Mechatronics directly to the 2nd year of BE.

For more infromation regarding Mechatronics as a career consider the link below:

https://www.careers360.com/courses/mechatronics-engineering-course

I hope this helps. Wish you a great afternoon!