You drop the Switch 2 into the dock, the console screen goes dark like it should, and then nothing. The TV sits on "No Signal" while the game keeps running somewhere you can't see it. Handheld mode works perfectly, so the console isn't dead. Something in the chain between dock, cable, and TV is failing the handshake.
The good news: this is almost always fixable at home. Here's the order I'd work through, starting with the causes that show up most often.
Try this first
Check the dumb stuff before the clever stuff.
- Confirm the TV input. Cycle through every HDMI input with the TV remote, not just the one you think the dock is on. Receivers and HDMI switches add a second place to get this wrong.
- Reseat both ends of the HDMI cable. Unplug from the dock and from the TV, then push each end back in until it's fully seated. A cable that's 95% inserted will fail intermittently or completely.
- Reseat the console in the dock. The Switch 2 needs to sit flush on the dock's USB-C connector. Cases and thick screen protectors can hold it a few millimeters too high.
That fixes a surprising share of these. If not, keep going.
Check the power adapter, not just the cable
The dock won't output video unless it's getting enough power. Nintendo's own adapter (model NGN-01) is rated for the job, and Nintendo says any adapter used with the dock should supply at least 54W. A phone charger or an older Switch 1 adapter can charge the console slowly in handheld mode, yet still leave the dock unable to drive a TV signal.
So: use the adapter that came in the box, plugged directly into a wall outlet. Skip power strips with USB ports and skip third-party USB-C hubs entirely for this test. If you've been docking through a travel hub, that's your prime suspect.
Force a fresh HDMI handshake
When the dock and TV get stuck mid-negotiation, no amount of replugging the cable clears it. A full power cycle does.
- Hold the power button on the console for about 12 seconds until it shuts down completely, not just sleeps.
- Unplug the dock's power cable and the HDMI cable. Wait at least 30 seconds so everything fully discharges.
- Plug the dock's power back in first, then HDMI to the TV, then seat the console.
This forces the dock and TV to renegotiate from scratch and clears the stuck-handshake state that causes most "worked yesterday, dead today" cases.
Swap the HDMI cable
The Switch 2 ships with an Ultra High Speed HDMI cable for a reason. The dock can output up to 4K at 60Hz, and 1080p or 1440p at up to 120Hz on supported TVs, and a tired or bargain-bin cable can fail to carry that reliably. One quick note on shopping: cables aren't sold by HDMI version number, they're rated by speed, and the badge you want on the box is Certified Ultra High Speed (48Gbps).
Test with the cable that came in the box if you still have it. If you've lost it, borrow one from a PS5 or buy a certified replacement before assuming the dock is broken.
If the picture appears, then drops
A signal that flashes up and dies usually means the console is outputting a format your TV (or the receiver in between) can't hold. Go to System Settings, then TV Settings, and drop the resolution to 1080p. If the picture is now stable, your TV or receiver is choking on 4K. Older receivers with HDMI 2.0 inputs handle 4K at 60Hz at most, so also try plugging the dock straight into the TV to rule the receiver out.
Recovery mode for stubborn output problems
If the TV shows nothing at any resolution and you can't reach the settings menu, the Switch 2 has a fallback. Power the console off fully, then hold both volume buttons and tap power to boot into the recovery menu, which forces a low-resolution mode most TVs will accept. From there you can update the system firmware, which has fixed dock compatibility bugs in past updates.
When the dock itself is the problem
If handheld mode is fine, a known-good cable changes nothing, the official adapter is on wall power, and recovery mode still gives the TV nothing, the dock's video-out hardware has likely failed. Docks do die while the console stays healthy. At that point it's a repair through Nintendo support, and worth checking your warranty status before paying for anything.