What options does my Nigerian friend have after his Thai visa was denied without a stated reason?

A Nigerian's visa to Thailand was denied without any reason provided, despite submitting all necessary documents and attending a physical interview. The comments suggest that there is no formal appeal process and that the individual might consider applying through another embassy. However, certain citizenships, including Nigeria, may face additional scrutiny and restrictions. It's advised to check specific requirements related to applications from Nigeria, as they may vary significantly. Additionally, contacting local Thai immigration or seeking guidance about potential reasons for rejection is recommended before reapplying.