Cristian,
You would need to heat the top corners of the enclosure for a few minutes with a hot air gun to soften the glue, lift the top off, and remove the LED grid. Then you would need to replace one of the surface mounted LEDs (the lens cover is a permanent part of each LED). Doing so puts adjacent LEDs at risk of heat damage.
Seeing as you just received it, I would try living with it for awhile and see if it affects your enjoyment. It really is quite common on Game Frames, due to the nature of the display. If you decide you’re not happy with it, I’d be happy to accept a return and refund you the cost (minus shipping/taxes).
Jeremy