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

**URL:** <https://forum.arduino.cc/t/have-no-hdmi-log-in-after-doing-full-upgrade/1443461>\
**Category:** UNO Q\
**Created:** [May 10, 2026, 3:13pm UTC](https://forum.arduino.cc/t/have-no-hdmi-log-in-after-doing-full-upgrade/1443461 "2026-05-10T15:13:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![gerrikoio](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/gerrikoio/32/1271182_2.png) [@gerrikoio](https://forum.arduino.cc/u/gerrikoio)\
**Post date:** [May 10, 2026, 3:13pm UTC](https://forum.arduino.cc/t/have-no-hdmi-log-in-after-doing-full-upgrade/1443461/1 "2026-05-10T15:13:55Z")

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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.

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**Author:** ![ptillisch](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@ptillisch](https://forum.arduino.cc/u/ptillisch)\
**Post date:** [May 10, 2026, 7:21pm UTC](https://forum.arduino.cc/t/have-no-hdmi-log-in-after-doing-full-upgrade/1443461/2 "2026-05-10T19:21:52Z")

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> [@gerrikoio](#):
>
> Is there no debug UART port like a Raspberry Pi?

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

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

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<div class="post-metadata">

**Author:** ![gerrikoio](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/gerrikoio/32/1271182_2.png) [@gerrikoio](https://forum.arduino.cc/u/gerrikoio)\
**Post date:** [May 10, 2026, 8:14pm UTC](https://forum.arduino.cc/t/have-no-hdmi-log-in-after-doing-full-upgrade/1443461/3 "2026-05-10T20:14:59Z")

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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?