Hi guys, I know I already shared this tech support site, but in this case it seem to fit too. If you only need to know if you need a serious repair or just a quick fix. I had problems with my camera and they showed me how to fix it with their free live chat support.
They have a very large range of products and many experts. I am sure you will find something. I even found some information about your problem.
Here is the page for
Nikon Coolpix 5400 Support I believe this is the same as your problem:
LCD blank & No picture takenThey say there it is a very common error for this camera and that Nikon is well aware of that but deny it related to the 5400 as well, I hope you will get it fix for free!
Good luck
Gracy