It's normal, some of them were fitted with green power light instead. That isn't a problem though, do you hear any drive clicking or any other indication that the machine may be working ?
You might need to reseat some chips, give them a gentle push back in their sockets. If there is still no display, swap out the custom chips from one of your working 500s to see if that works. Also, don't forget to swap the power supply & video cables to see if that's the problem.
