Light boards... satan's work!
Check the connection on the car and ensure there's no oxidisation on the terminals. Use a little brake cleaner and fine 3M paper to remove.
The light board, unscrew the plastic lenses and check the bulb terminals actually make contact. Finally check the connection on the light board flex that connects to the car. The plastic ones you can open up. Check for obvious things, loose wires, etc. Then and only then... consider a new light board!