Yes, you can file the mandamus case in court yourself without a lawyer. Almost 90% of cases get resolved without a court hearing and hence it should be your first step. If needed, you can appear for a court hearing yourself (it's a simple one) or you can hire an attorney at that time.
Writ of mandamus cases have a high success rate, with 99% of cases being processed and submitted faster without contestation in court. However, the success of the petition itself depends on the specific factors of the case. A writ of mandamus forces USCIS to make a decision but does not guarantee approval.
If you choose to defend yourself, you must file the Notice of Intention to Defend, appearing on the bottom half of the summons. The Notice should be cut at the perforated line and returned to the court address listed at the top of the summons.
(1) A party petitioning for a writ of mandamus or prohibition directed to a court must file a petition with the circuit clerk and serve it on all parties to the proceeding in the trial court. The party must also provide a copy to the trial-court judge.
File the Petition for a Writ of Mandamus at the circuit court. There is no form for filing a Petition for Writ of Mandamus. You may want to visit a law library to locate a sample of a Petition for a Writ of Mandamus. More information on the law libraries of Maryland can be found at mdcourts/ccll.
Conclusion: Going to small claims court may be worth it for $500, but it will determine how you weigh your costs versus benefits. At a minimum, it is worth it to send a demand letter.