How to change the color of an object in a photo

[Ofnuts]

Any uniform color is going to show out. My suggestion:

• Create a square layer (side size: about the height of the panel)
  
• Set the brush to "Dissolve" mode and medium opacity
  
• Fill it with random strokes of colors
  
•    
  
• Use the Perspective tool to map the layer on the square
  
•    
  
• Use Contrast to reduce contrast so the panel blends better
  
• Use a layer mask to left the arm show
  
•    
  

(low quality JPEGs to keep image file size under the 500K limit)