Welcome to the Roku Community and thanks for posting regarding the issue you are experiencing related to your Express 4K device.
Please be aware that the overheating issue you are experiencing is unrelated to the error code you are seeing appear on screen. The error code you are receiving is related to poor connectivity to your wireless network.
For more information about both overheating with Roku devices and the error code, visit our Support pages here:
Fix an overheating issue
Set up or fix your internet connection
If you need further assistance with the issue you are seeing, please feel free to post again in the Roku Community.
Roku Community Moderator