HDMI not working on RBPi4b

Installation
1

Hi

Today I lost connection to my HA system that is installed on a raspberry pi 4B so I tried restarting it. It didn’t work at first so I connected it to a screen to see if there was anything wrong in the commands screen. But although the screen detected signal from the RBPi4b, the screen was completely black. If I disconnect the hdmi cable from the RBPi4b I get the “no signal detected” on my screen so it seems that the cable is ok and the pi is sending something but it’s only s black screen

I tried restarting again and not my HA it’s working properly but I cannot see the commands in my screen through the HDMI

Is the anything to check/test in order to discard a HW failure?

2

Hi agak79,

Well if it’s not booted at all, that’s what you will see.
Possibly has your SD card worn out?
Is the power OK?

3

Hi

I have the ha installed on a SSD too avoid the known problems with the SD cards.

After a second restart I can access to my HA installation but the HDMI is still not working.

4

Try another HDMI cable. Seriously. Also, don’t use an HDMI selector switch, go directly from the Raspberry to the monitor.

5

It is connected directly to the screen but I’ll try another cable.

6

On older Pi’s, I always had the problem that the HDMI needed to be connected before boot to have something on the screen.

7

If the OP and your past experience was using an HDMI television, this is the HDMI protocol attempt at being “smart”. If you have two HDMI inputs on your TV, one for the set top box and one for the DVD player, the “smart” HDMI TV will automatically select whichever device is turned on.

8

No, HDMI Computer monitor (with only 1 HDMI input)

9

Did anything resolve with this? I just experienced a similar loss of HDMI in Home Assistant after upgrading. I was originally running OS 17.0 and Core 2026.1.x. I had blocked there due to the potential USB issue upgrading to OS 17.2.
I finally got around to upgrading the bootloader, using the boot on alternate SD method. I upgraded to OS 18.1 and Core 2026.7.4. From browser access, everything is fine, but I did notice the lack of the usual ha> prompt on the monitor.
If I reboot, I do see the bootloader on HDMI, followed by the initial kernel messages, but the display quickly goes blank and never displays again.
If I boot a regular RPi OS display is fine.
Raspberry Pi 4 Model B Rev 1.4