Black screen, no device, no popup. Before you return the card, run this list in order - most dead setups come back to life at step two or three.
A capture setup has five parts, and a not-detected fault can be caused by any of them - which is why random fiddling wastes so much time. Work this page top to bottom. Each step eliminates one whole link of the chain, and the early steps are the ones that fix most cases: connection direction, a cable that secretly carries no data, and an app that was opened too early.
Capture cards are one-directional. The HDMI cable must land in the port marked IN (from the PC), and the USB side must face the phone. A chain assembled backwards produces exactly your symptom: nothing, anywhere, with no error message. Unplug everything and rebuild it slowly, reading the labels on the card itself, not the listing photos.
While you are there, push every connector fully home. USB-C plugs that stop a millimetre short - often because of a thick phone case lip - are a classic silent failure. If in doubt, remove the phone case for the test.
If any link in your chain is a loose USB cable rather than a fixed adapter, suspect it now. Many cables bundled with chargers are charge-only: they carry power and no data at all. The capture card can even light its LED from such a cable - powered, and completely invisible to the phone.
Swap in a cable you know carries data - the one that successfully copies files between the phone and a computer is a proven witness. This single swap resurrects more "dead" capture setups than every other fix combined.
Some Android brands hide an OTG toggle in settings (often under connection or additional settings), and it may be off by default - or may switch itself off after several minutes without use, which produces the maddening "it worked, then it stopped" pattern. Turn it on, then reconnect.
Also watch for the USB permission popup when the app opens: if it appeared once and was denied or dismissed, the app may stay locked out. Clear it by unplugging, force-closing the app, plugging in again and opening the app so the prompt returns - and this time allow it.
Viewer apps typically scan for USB devices when they start. An app opened before the card was plugged in may sit forever on its own camera. Rule: plug everything in first, power the PC so it sends a picture, and open the app last. Force-close and reopen counts as fixing the order.
Still nothing? Now split the chain in half: plug the capture card into a computer and open any camera app there. If the PC shows the feed, card and HDMI are proven - your problem lives in the phone half (OTG support, adapter, app, or the phone simply not supporting USB cameras). If the PC also shows nothing, feed the card a different HDMI source before blaming it - a PC set to a disconnected output can send nothing at all.
The video shows the complete working connection sequence - compare your order against it step by step if your setup stays dark.
Watch Full VideoNot proven. The light only proves power is arriving - and power can arrive through a charge-only cable that carries no data. Swap the cable, confirm OTG is on, and reopen the app after plugging in before judging the card.
The usual suspects are an OTG setting that switched itself off, an app update, or a denied USB permission remembered by the system. Re-run the order in this page: OTG on, everything plugged in, app opened last, permission allowed.
No. OTG and USB camera support are hardware and system capabilities. An app can only use what the phone provides. If your phone lacks it, the honest options are a different phone for this job or a small portable monitor instead.