After changing a parameter Blanchard & Kahn conditions are not satisfied

[jpfeifer]

I am sorry to hear that. But that sounds like a big problem with supervision. See e.g.

Replication of "Countercyclical Capital Regulation in a Small Open Economy DSGE Model" of Matija Lozej, Luca Onorante, and Ansgar Rannenberg

That depends on your background. If you have not worked with DSGE models before, then I would plan with at least 6 months. You will also need proper supervision, i.e. someone to turn to in case you encounter problems. If that is not assured, I would not try to do this.

and

Help me how to learn DSGE model

Here is my standard answer in such cases: Students are not supposed to work on models that complicated without intense supervision. I have seen too many cases like this miserably fail. Most of the time, the goals set are too unrealistic given the prior training and the time frame envisioned. The paper you have in mind is rather infamous for being extremely hard to replicate.

So any grading should take that failure of supervision into account.