At the hearing, the landlord will have to explain to the court why the work was not done. If the work is partially completed, the judge may allow additional time. If this is acceptable to you, continue to insist on a firm deadline for completion of the work, and provisions for another return date for the court to monitor compliance. If the landlord still does not perform, you can ask the court to take further measures. The threat of fines can leverage the landlord into action.
Fines can become a lien against the landlord's properly.
Again, tenants should involve themselves in any negotiations involving fines. In even rarer cases, landlords are jailed for contempt of court. Contempt motions can be brought by tenants or HPD, but tenants may need a lawyer to succeed. During these hearings, landlords may complain that they tried to make the repairs and the tenant did not provide access to the apartment. How HP cases should be handled and resolved in court and what actually happens are usually very different.