Have no HDMI / log-in after doing full-upgrade

Official Hardware UNO Family UNO Q
1

I was in App Lab settings and it said my OS needed updating but the "update" button did not do anything when clicked. I tried this more than 3 times and even restarted the board 3 times and at no stage did anything change. No message... nothing.

So I opened up terminal and did a sudo apt update and then a sudo apt full-upgrade.

No errors were flagged during the upgrade.

I then did a shut down and then powered the board up again.

This time nothing.

I did not see any bootup log. The HDMI display does not power up.

I am now locked out my Arduino Q.

Is there no debug UART port like a Raspberry Pi?

How can we expect to rely on HDMI/USB C drivers etc. if this is going to happen.

Any guidance welcomed.

Thank you.

2

There is one. It accessed via the 2x5 "JCTL" male header:

https://docs.arduino.cc/tutorials/uno-q/user-manual/#hardware-debug-uart-interface

3

I'm putting this down to general unreliability as it eventually came back after having powered off the Arduino-Q and returning to it hours later.

However, I still have App Lab saying my OS is behind.

I checked and I have the latest Debian 13.4, but it looks like the kernel is still the original load from Aug 2025 (version 6.16.0).

Is it advisable to upgrade the kernel to 6.18?