Sorry, but can you please be more specific?
- Did the WiiU run correctly before?
- What did you do at last before? E.g. some custom modification, modified some files, opened the WiiU.
- Has the WiiU a CFW? Haxchi/CBHC or Tiramisu?
- What appears on the screen? E.g. a autoboot information, just black screen or WiiU logo.
- If CFW, can u enter a boot menu?
> on CBHC: Hold "sync" on console or "home" on pad when "autobooting..." appears.
> on Tiramisu: Hold "start" at boot.
- Did you unpluged every cable and reconnected them to fit them correctly?