I'm using a rapsberry pi 4 with the original power supply. Everything was working with the pi and then one day I turn it on and it no longer works. When I turn the pi on the red light is constantly on, the green light doesn't turn on at all. I've re-written the SD card with the raspbian OS, still nothing. I've tried turning the pi on without the SD still a blank screen. I don't think it's the HDMI cable because the entire setup was left alone and now it's not working. Also tried it on another monitor and I still get nothing. The hdmi port that the cable is connected to is hdmi0. I've also tried setting the hdmi_mode = 16 in the config.txt and it still doesn't work. Shouldn't the pi show something even when there's no SD card?