I just put together a new 5 Pro and I got the TMC error. I then got the recommended firmware update and put it in the machine and the error was gone but now the thing flashes the logo screen like its rebooting in a loop and makes a terrible loud beep sound. Thoughts?

I just got this Ender 5 Pro and same issue. TMC connection error. I downloaded and performed the firmware update and now the error is gone but machine software keeps rebooting and there is a loud beep noise. Also where do I find the serial number for the machine?