Press and hold the power button on the
and your Wii will go into standby mode with Standby Connect on. The light will be orange/yellow.
While in standby mode, the Wii U will: Continue to download items currently downloading in Download Management, including content purchased from the Nintendo eShop, system updates, software updates, and add-on content. Regularly connect to the Internet to check for available SpotPass data or software and system updates.
Using the Left Stick, scroll to the “Power Settings” icon and press the A Button. Select “Standby Functions,” and then “Enable” or Disable.”
After 60 minutes by default the Wii U Console is set to turn completely off. This can be a problem for those who don’t know about this feature. This can be turned off, or the time in which it takes before it turns off can be extended, by changing it in the “‘System Settings”.
You’re correct. It’s pretty much Sleep Mode for the Wii U. They just officially call it Stand-By Mode.
We’re sure it’s absolutely safe to leave the Wii “off” with a yellow light on the power button, but our irrational fears have caused us to make sure our system is totally off every night by first changing the Standby mode feature through the Wii’s settings into the off position and holding down that power button until …
Orange/yellow – the Wii is in standby. WiiConnect24* will continue to work during this time. Red – the Wii is switched off but is still receiving power.
Complete these steps
Remove any game cards or microSD cards from the system. Press and hold down the POWER Button for three seconds, then select Power Options followed by Turn Off. If the system does not respond, press and hold down the POWER Button for at least twelve seconds to force the system to shut down.
The yellow light indicates that the Wii is off but the WiiConnect24 is on, operating in standby mode. You can turn this light off by going to (Wii Icon) > Settings > WiiConnect24 > WiiConnect24 > Off and select Confirm. At times, you will also see the Wii’s disc slot glow.
Faulty Bluetooth Board. The Bluetooth or Wi-Fi boards could have been damaged or disconnected from the motherboard causing the console to shut off. You have to reset or replace them to get the Wii to start.
The outer case of the Wii would be hot to the touch after the shut-off. The obvious diagnosis was that the Wii was overheating, and powering itself off as a safety measure to avoid damaging the processor or other internal components due to the very high temperature.