How to replace my uverse wired box it's old black unit boots to black screen with red X and #1

Call Customer Service 1-800-288-2020.  If they determine that it has issues, a new box will be sent to you for a self-install. 

You have 21 days to return the bad one via UPS/FedEx.  You should be emailed with instructions.

Try the troubleshooting steps described here.  If that doesn't fix it, and with that error most likely won't, you shouldn't have any problem getting it replaced through tech support (800-288-2020).  For the dvr you lose all your recordings (lost anyhow) but not your scheduling.