I have my Roku Ultra connected to the HDMI port on my Sharp Aquos TV. After the 9.4 software upgrade was pushed the HDMI interface stopped working. During the power-up sequence, the Roku logo is displayed on the TV then the screen goes blank. I connected my laptop using the same HDMI cable and can view the desktop on the TV with no issues. Have also connected the Roku via HDMI to an LG smart TV and have no issues. Roku seems to work fine with the LG TV just not with the Sharp Aquos. Have been using the Sharp Aquos with the Roku Ultra for over a year until 9.4 rolled out and now nothing. TV still works using the same HDMI and video inputs now just not with my Roku Ultra with 9.4. Roku support says it is the TV even though the TV is working with other devices. They made an "improvement" that has turned out to be detrimental to older TVs with HDMI inputs. They have obviously "tweaked" the HDMI interface and now it is no longer fully compliant with the interface standard. Disappointing.
Make sure you report/press the issue directly with support:
Chat or email: https://support.roku.com/contactus/contact-options (choose setup/ultra/other/need more help)
and/or message @RokuDanny-R
Thanks for the post.
If you are already in touch with our Support team. We would recommend continuing to work with them to see what troubleshooting steps they can provide you as they would best be able to assist you.
Thanks,
Danny
Maybe the auto detection of resolution broke. Move the Roku to the LG and force the resolution to stay at 720p, reconnect to the Sharp Aquis.