Hello Aspirant...

In this case Firstly you can consult your seniors or college administration about the stream change because in many colleges it is allowed to change your stream in second year based on the marks of first year

Secondly you can prepare side by side for coding all types of languages(I would suggest) and many basics of the CSE and prepare for your placements as company would not hesitate in taking a ECE student having knowledge of CSE because they will think why to pay for two different persons for different works if the works are done by a single person.

You can also appear for CSE branch in GATE exam because rules are changed that you can give one more stream exam other than main stream then bring good marks and get placed.

and lastly,

According to your ranks in jee advanced ranks you may get many other and good colleges like IIITs , central government universities or government aided colleges If you are of a general category student

https://engineering.careers360.com/articles/jee-main-cutoff-for-top-iiits

and many more