Dear Brooklyn Tenant:
If the City ordered the closing and locking of the entrance to the cellar the use of the cellar as a secondary means of egress should have been part of the decision process. The fact that the City caused the closing of the entrance to the cellar eliminates the idea that your landlord is retaliating against you.
You may call for an inspection using the city's central complaint number 311.
Your landlord should call the local firehouse for an inspection to learn whether the cellar must be accessible as a means of egress in an emergency.
If you landlord will not make the call, you could call for a follow up inspection.
The answer provided to you is in the nature of general information. The general proposition being that you should try to avoid a bad outcome if you can.