Hey! We’ll get your security camera DVR/NVR HDMI output working again and stop the monitor/TV from showing “No Signal”, “No Input”, or “Mode Not Supported”.

Quick questions so we don’t guess:
• What device is it: DVR (BNC/coax cameras) or NVR (IP/PoE cameras)? Brand/model if you know (Swann, Lorex, Reolink, Hikvision, Dahua, Night Owl, etc.).
• What screen are you using: TV, PC monitor, or CCTV monitor? Is it 1080p only or 4K?
• Do you get any splash logo on boot (brand logo), then it goes black — or is it no display from power-on?
• Are you connected by HDMI only, or do you also have VGA available to test?

These details tell us whether it’s a resolution/EDID mismatch, a cable/port issue, or a recorder output setting.

Thanks — “logo once, then nothing” is a classic clue. When a security DVR/NVR shows no video output on HDMI, the top causes are:
• Output resolution not supported by the TV/monitor (common after a power outage, update, or when switching displays).
• HDMI handshake/EDID problem (TV doesn’t “agree” with the recorder).
• Bad/loose HDMI cable, wrong TV input, or a flaky HDMI port.
• Recorder not booting fully (power adapter, front panel LEDs, or storage issue).

We’ll fix it in the safest order first: power + cable + port → confirm the recorder boots → force a supported resolution → reset display settings if needed.

Perfect — let’s do the “first-minute” checks that fix most DVR/NVR HDMI no signal problems without changing settings.

Step 1 — Power cycle in the correct order (handshake reset)
1) Turn the TV off.
2) Unplug the NVR/DVR power adapter from the wall for 30–60 seconds (don’t just press the button).
3) While it’s unplugged, disconnect HDMI from both ends and plug it back in firmly (you should feel it seat).
4) Power the TV on first and select the correct HDMI input.
5) Plug the NVR/DVR back in and wait 2–3 minutes for full boot. Watch for a logo or change on screen.

Step 2 — Quick HDMI port / input sanity check
• Try a different HDMI port on the TV (HDMI 1 vs HDMI 2).
• If your TV has “HDMI Enhanced / UHD / Deep Color” mode, leave it on default for now (we want basic compatibility).

Tell me: after the proper power cycle, do you see any splash screen at all?

Got it. Next we isolate whether this is the TV/HDMI path or the recorder output itself.

Step 3 — Swap the HDMI cable (fastest way to eliminate the obvious)
• If you can, use a different known-good HDMI cable (even a short one). A slightly damaged cable can still “sort of” work and then fail.

Step 4 — Try a different display (TV vs monitor)
• If you have access to any other screen with HDMI (another TV, a PC monitor, even a small spare monitor), connect the NVR directly to it.

Step 5 — Confirm the recorder is actually booting
• Look for a Power LED and HDD/Status LED activity (some units blink during boot).
• If the power adapter has an LED, make sure it stays lit (a failing adapter can power fans but not output video reliably).

If a different cable/display still shows NVR no video output, the most common “real” cause becomes output resolution set too high (e.g., 4K on a 1080p TV) or a display setting glitch we need to reset.

That’s strong evidence it’s not the TV or HDMI cable — it’s the recorder display output (usually resolution/format). This happens a lot after changing TVs or if the NVR previously ran on a 4K monitor and now it’s on a 1080p TV.

Step 6 — Fix “No signal / Mode not supported” by forcing a supported output
The cleanest method is temporarily connecting by VGA (or another supported output) so you can lower the NVR/DVR resolution and then switch back to HDMI.

What to do (typical path on many NVR/DVR brands):
1) Connect the recorder to a monitor using VGA (borrow a VGA cable if needed).
2) Log in with mouse/keyboard (most recorders require a USB mouse).
3) Go to Menu / System / Display / Output (names vary: “GUI”, “Display”, “Screen”, “Monitor”).
4) Set HDMI/GUI resolution to a safe option like 1280×720 (720p) or 1920×1080 (1080p) — avoid 4K for testing.
5) Save/apply, reboot if prompted, then reconnect HDMI to the TV.

Keywords you’ll see around this problem: DVR HDMI black screen, NVR no display, HDMI output not working, resolution not supported — and the fix is almost always to drop the output resolution.

Yes — some recorders let you recover display without a menu, but it depends on the brand. Here are the safe options that don’t involve risky “secret” tweaks.

Step 7 — Look for a physical reset / default button
• Many NVR/DVR units have a small reset pinhole on the back or inside the case (sometimes labeled RESET).
• If your model supports it: power on → press/hold reset for ~10–15 seconds → release → wait for reboot.
This can reset display output to a default resolution that most TVs support.

Step 8 — Remove conflicts: disconnect extras and test “minimum boot”
1) Power off the NVR/DVR.
2) Unplug everything except: power + HDMI (no USB drives, no network switch add-ons, keep it simple).
3) If you can access the HDD bay safely (no tools if it’s a slide-out bay): temporarily disconnect the hard drive and test boot to HDMI. A failing HDD can sometimes stall boot or freeze video output on some recorders.

Step 9 — Power adapter reality check (very common)
Even if the adapter LED is on, it can still be weak under load. If you have another adapter with the exact same voltage and correct plug/polarity (usually 12V or 48V depending on model), testing a known-good adapter can bring back stable HDMI video output instantly.

If you tell me the brand/model (or a photo of the sticker specs), I can point you to the exact “display reset” method that brand supports.

Reolink PoE NVR — perfect, that narrows it. Yes, it can absolutely still be a video output resolution mismatch or a display handshake problem, especially if the NVR was ever connected to a different monitor/TV before.

Here’s the practical reality for many NVRs: if the configured output is unsupported, the TV may show No Signal or a black screen even though the NVR is running normally.

Step 10 — The fastest “wins” for Reolink NVR no display
• Try a different monitor (PC monitor is often more forgiving than a TV). Some TVs are picky about handshake and timing.
• If the TV has a “Game Mode” or “PC Mode”, try it — it can improve compatibility for odd HDMI timings.
• If you can borrow a VGA cable/monitor temporarily, do it — it’s the most reliable way to get into the menu and set output back to 720p/1080p.

Step 11 — When the NVR boots but HDMI stays dead
• Test without the HDD once (power off → disconnect HDD → power on). If HDMI output appears after removing the drive, the HDD or file system may be causing a boot/display hang.
• After you regain display, update NVR firmware from the official support path to reduce recurring HDMI no signal issues and improve stability.

If you can share whether your TV is 1080p or 4K, and whether you ever used this NVR on a different screen, we can be very confident it’s the output setting.

That explains it. If it was last used on a 4K TV, the NVR may be set to a 4K output timing your 1080p TV won’t display — resulting in security camera no signal on HDMI even though everything else is fine.

Good news: you usually do not need a full factory reset. You just need to lower the HDMI/GUI output resolution.

Step 12 — What to do once you borrow VGA (recommended)
1) Connect the NVR to a monitor via VGA (or to the 4K TV temporarily if that still shows video).
2) Go to Display / Monitor / Output settings.
3) Set resolution to 1080p (or even 720p for testing). Apply/save.
4) Reboot the NVR if prompted.
5) Move back to the 1080p TV via HDMI — it should now show video instantly.

When to factory reset:
• Only if you cannot get any display on any screen and the unit won’t respond normally, or settings are corrupted.
• If you reset, you may need to re-add cameras, recording schedules, and network settings — so we avoid it unless necessary.

Love it — that’s the most common real fix.

Summary: when a security camera system shows “No Signal” on HDMI, start by power-cycling TV + DVR/NVR, reseating the HDMI cable, and trying a different HDMI port. If the recorder is running but you still get a black screen, the usual cause is output resolution not supported (often set to 4K while the TV is 1080p). Use a VGA/alternate display to get into the menu and set the recorder to 1080p or 720p, then reconnect HDMI. If nothing shows on any display, test the power adapter and (optionally) boot once with the HDD disconnected.

Want help finding the exact Display / Output / HDMI resolution menu for your model (Swann/Lorex/Reolink/Hikvision/Dahua)? Open the chat and an expert will guide you in real time.