Welcome to the forum, as a newbie your initial posts are monitored, so it will be a while before you can respond. You have a short and the cab is turning itself off when connected to the mailine.
You might have feeders connected to the wrong track or you might have a heretofore unrecognized reversing loop or a tool lying across the track. I agree with changing the title of your thread, it also makes it searchable for people with the same problem in the future,.
Henry
COB Potomac & Northern
Shenandoah Valley
Change the title to your thread from Wiring My Layout to Problems with Power Cab.
That may well draw more attention to your need for help.
Good luck.
Rich
Alton Junction
Hi, I have just wired my layout with the NCE 50 ft double mainline wiring kit. I also have the NCE Power Cab. I currently have only two locomotives with DCC and sound but plan on getting more. When I finished wiring my layout, I tried it out but the Power Cab only showed the screen that has the cab address and the version. Then it will turn off and continue to do that until I unplug it. I do have a programming track that is not connected to the mainline in any fashion, it's isolated by itself and the power cab works just fine on that. So I don't really know what is going on and I'm asking for help. Thanks!