Concerning my experience with Epson SureColor P800 Error Code 0x1A36 ...
Printer worked after initial setup.
One day later I updated the firmware from the desktop application and it was still responsive, although I didn't run any test prints at that time.
Subsequently, while setting up Epson Connect from a phone app, the app indicated that there was another firmware update. I initiated it from the phone app. At that point, the printer became unresponsive, displaying the error code 0x1A36 on the panel.
After powering down/up the error code message was re-displayed after a brief EPSON logo.
Attempting to restart the firmware update from the desktop via WiFi would only get to 14% completion, then an error indicating that it could not be done.
Epson technical support had me try to to update the firmware with a direct USB connection. This also failed after 14%.
Because I had purchased the printer under 30 days ago, they initiated and sent an overnight replacement. They indicated that if it had been over 30 days, they would have accepted the printer for analysis and repair instead.
They said there was nothing I did that I shouldn't have done. Although I think I will steer clear of initiating firmware updates via phone apps in the future.
Kudos to Espon for a 30-hour turnaround time from phone call to receipt of printer.