Yes, still getting HDMI (box) messages on Raspberry Pi screen.
With no card installed HDMI fires up and moves to ‘trying boot mode’ and following the esc prompt at the bottom of that screen I get a diagnostic text message which includes ‘boot loader … failed’ every 25 seconds
With new card installed (created with Raspberry Pi Imager) HDMI text box fires up, followed by a multi-coloured screen which instantly changes to a flashing ‘-’ prompt on a blank screen. This response repeats continuously.
With a card which works perfectly on a Pi3B I get a ‘Welcome to RaspberryPi desktop’ screen which then disappears and the cycle repeats.
It sounds like its boot cycling when any SD Card is installed.
In addition to trying to boot it from the USB (so we can rule out if the SD Card is the problem) could you please follow the steps in the below to update the Pi 4’s Bootloader. It’s possible the eeprom on the board has become corrupted.