I have a raspberry pi4B with a TS7-Pro Touch screen. After I updated to Trixie, I get “No Signal” displayed on the screen when pi boots. Prof. Google told me to put lines like:
hdmi_force_hotplug=1
dtoverlay=vc4-kms-v3d
in the config.txt in the pi’s boot partition, but it didn’t help. Does anybody know what the problem is?
Could you please provide more details about the issue? After your Raspberry Pi boots up, does the screen only show “NO SIGNAL” with no image at all?
Also, can you check the LED indicators on the Raspberry Pi? Is the green LED (activity) blinking?
If possible, please take a clear photo showing both the power LED on the Raspberry Pi and the screen displaying “NO SIGNAL”, then send it to me. This will help us understand the situation better.
Thank you for your patience and cooperation.
Thanks for the reply. Red LED is on, and green LED is blinking. I have a video of it, but “new users” can’t upload attachments.
If the red LED is solid and the green LED is blinking, this typically means the Raspberry Pi is powered on and the system is booting.
Therefore, the issue is more likely related to HDMI display output rather than the Raspberry Pi failing to start.
Additionally, we have tested the setup with Raspberry Pi 4B + TS7-PRO + Trixie system, and the display worked normally. So this is not a general compatibility issue between the TS7-PRO and Trixie.
Could you please help confirm the following:
Are you using an HDMI cable or an HDMI adapter? Try swapping the connection.
Is the HDMI cable connected to the HDMI0 port on the Raspberry Pi 4 (the one closest to the USB‑C power port)?
Are you using the /boot/firmware/config.txt file?
Have you added any other HDMI‑related forced configuration settings?
Is the power supply stable enough? (Recommended: 5V 3A)
If possible, please upload a short video or a few photos to OneDrive or a similar service, and share the link with me.
Thank you for your cooperation.
I tried a cable and it worked, and when I re-inserted the coupler it worked. Maybe the contacts had oxidized or something. I hadn’t used it for a few years. Add that to your troubleshooting – remove coupler and re-insert. 
Thanks for your time.
Congratulations on resolving the issue, and thank you for sharing your solution.
Your suggestion is very helpful. We will remind other users to reseat the connectors if they encounter a similar problem.