These are some troubleshooting steps for no image on the HDMI output for the Raspberry Pi 4 board. If these do not fix the issue please contact us with your order number and we will assist you.
1. The HDMI cable is connected to the wrong HDMI port.
When using a single HDMI connection, the cable needs to be connected to HDMI0 Port closest to the Power Port. IF the cable is connected to the other HDMI Port then you will see a rainbow screen only. (this issue is for a Raspberry Pi 4 only)
2. The SD card
If the SD card you are using is not properly flashed or corrupt this would not allow the Pi to Boot.
The Best way to check the SD card is to turn the Pi with the SD card installed and look at the lights on the board. You should see a red light turn on and stay on, followed by a flashing green light that should turn on sty on periodically.
If you do not see the green light go on at all or if the green light just flashes repeatably and does not stay on for more then a second this would indicate that the board cannot read the card and that the SD card is faulty.
If the SD card is faulty we recommend that you reflash the SD card.
If you need information on how to properly flash an SD card please see the link below:
We recommend using the raspberry pi imager software for the best results.
If you have checked the HDMI connection and the SD card and confirmed that both are properly connected/flashed and you still cannot boot then please get back to us so that we can further troubleshoot your issue.
Thank you and I look forward to hearing back from you.