Keeping the screen on indefinitely

[Carpeniton]

I just picked up a Lumia 900 off Ebay, refurbished, and as much as I love it, the home screen tiles from the last user (I'm assuming) are burned into the background, pretty vivdly. It really interrupts a lot of functions, especially the camera where there is a ghost home screen over top. I'm trying to fix this with a stuck pixel app that runs a strobe, but the phone screen turns off every 5 minutes so I can't really leave it on overnight.
Is there any way to fix this? Either a better solution to get rid of the screen burn, or keep it from turning off automatically? (Options I have in the settings are 30sec, 1min, 2 min, 5min, no Never option)

Thanks!

 

[Laura Knotek]

Is the device branded to AT&T? I have an AT&T 900, and I've never had the option to leave the screen on indefinitely.

 

[Carpeniton]

Yes it's AT&T, there's no option that I can find to do it but I figured there might be an app or something for it.
Worst case scenario I'm going to try and force the ebay seller to send me a free replacement screen, I don't feel like re-customizing another phone right now so I'd rather find some way to fix this one.