I have the same issue, my new board worked great for 3 weeks and then I got the blank blue screen when I turned it on today. there is a darker blue rectangle in the area a few centimeters from the outer frame.
The power to the Ender 3 is fine, red light on the board and green light at the SD card slot.
I connected a USB cable to the mini port and my computer does not detect anything. This powers the board, red light comes on, but no connection.
I have tried several SD cards, ensured they were FAT32 etc, nothing worked to try to flash the firmware again.
Any thoughts from anyone appreciated.