[mothered]

As far as i know, its claiming your device isnt working correctly due to an error

Correct.

Simply claim It's defective.

  and maybe a POP ( proof of purchase )

Don't fake It, It's extremely likely they'll cross-check Its authenticity.

then if the device is un warranty

It must be under warranty.

That's how the serial number method works - a warranty claim.

they could ask for a POD

Photoshop It.