Hello aspirant,
A CUET score of 400 is a decent score, but securing admission to SPMR (BCom) might be challenging in the general category. However, you might have better chances in the subsequent rounds of counseling if seats remain vacant. You can consider other good colleges offering BCom with a similar or lower cutoff.
You can consider the following;

Wait for Cutoffs: The official cutoffs will be released by the concerned authorities.
Check Other Colleges: Explore other colleges with suitable cutoffs and course offerings.
Consider Other Options: If BCom doesn't work out, consider other relevant courses.

I hope this information helps.