It happens to me to with WinCE 600 when I press power button, and I investigated it in serial output and it seems it does not pass the bootloader stage, and I mean it doesn't reach the point in which it loads the WinCE image. That is because, in my case the power goes down immediately after I release the power button. It works though if I hold the power button pressed or if I plug whatever usb cable(so it can draw power from it). Anyway, in your case I think the nboot.nb0 is not the wright one. Producer.nb0 doesn't make sense to be the problem since it does pretty much nothing at boot time(it handles .nb0 files download and partition manager for flash), but eboot.nb0 on the other hand might be with problems because is the one calling the start-up functions for WinCE. Check if you have the proper board for V1.90 rom files, it should work, in my case worked from the first try. If you have other board try with the other versions available form CMN