dehumidifiers have a compressor. The compressor cools coils. Air is drawn over the coils lowering the air temp below the dew point and water condenses out. The air is then passed over the compressor coils and the compressor heat is removed.
When the unit is working, warm air is blown out.
Therefore, your compressor is not functioning, and the air coming out is the same temp as what is going in.
WHY?, likely a bad compressor, but it could be an issue with the control board not powering the compressor.
Disassembly required, and troubleshoot with your DVM.