On a handful of our boards now we have lost the use of our HDMI port and had to SSH into the board to find the i2c isn’t working either. Not sure the reasoning for it we are using them with some arduino megas with the i2c. Any tips or if it is covered by warranty would be super helpful info thanks.
HDMI queries the monitor for its capabilities in order to know what video settings to use. If that query fails, then some default or fallback setting might be used. The wire used for this query is the DDC wire, the data is “EDID”, and the protocol used is i2c. If the i2c controller is somehow being changed by your i2c, then this would cause video to stop working in cases where the default video mode doesn’t work with that monitor.
You can see if i2c is working properly via:
sudo -s
cat `find /sys -name edid`
exit
What do you see from that? If you copy and paste the hex data into http://www.edidreader.com, does the checksum show as valid?