These two messages mean different things, and what to do depends on whether you have added or changed any music yourself.
If you have not touched the files - start here
This is the most common version of this problem. You built Jay-D, you are using the micro SD card that came in the box, you have not added or removed anything, and Playback still says Empty! - often after showing "SD card" and "Loading..." for a moment first. Many people also confirm on a computer that the factory tracks are still on the card.
If that describes you, stop troubleshooting and tell us. The card and the files are not the problem, so the steps below will not help, and we would rather look at it than have you keep trying things. Message us here, or email [email protected], with your order number, whether you see "Empty!" or "Not inserted!", and a short video of the screen from switch-on to the message appearing.
Please do not spend time on these first - people have tried them and they do not fix this case:
Re-downloading the factory SD card content and copying it back on.
Converting the tracks to WAV or MP3. The factory files are already in the format Jay-D expects, and converting them makes things worse rather than better.
Reformatting the card that came in the box.
Looking for a reset button. There is not one.
"Not inserted!"
This means Jay-D cannot read the card at all: it is missing, not pushed in fully, or damaged. Switch off, take the card out and push it back in until it clicks. If you are using a card of your own rather than the one from the box, check the filesystem - Jay-D reads FAT32, and exFAT will not mount. If the card from the box gives you this message even when it is properly seated, tell us rather than reformatting it.
If your card is lost, or has stopped working
You can download the factory SD card content and copy it onto a replacement card: Jay-D's SD card content. This is the right fix when the card itself is gone or has failed - it is not a fix for a working card that still reads as "Empty!".
If you have added your own music
Then "Empty!" usually does mean Jay-D found nothing it recognises. Per our build guide, Jay-D plays .aac files and skips MP3, WAV, M4A, FLAC and OGG - they stay invisible in the song list even though you can see them on the card from a computer. The guide also specifies mono at 24 kHz; other sample rates play at the wrong speed and pitch, and stereo files play back garbled. Files can sit in the root or in any folder at any depth, because Jay-D searches the whole card.
If you are not sure whether your files match that, send us one of them along with your order number and we will check rather than have you guess.
One thing that is not a card problem
If any part of the board or the batteries becomes hot, stop using Jay-D, unplug it from USB and from any charger, and tell us straight away. Do not keep testing it. That is a safety matter and we will pick it up with you directly.