Have TV Questions? Ask a TV Technician
Hello Richard, I'm Shahid. Sorry to hear that you're having trouble with this but I'll do my best to help.
Your diagnosis seems correct and remote sensor could be cause of problem. I would recommend to cover the remote sensor located on lower front of TV with dark tape (for example black tape) to make it blind and check if TV powers up itself, this test will confirm the remote sensor issue.
I hope these info will help. If you have any additional questions, feel free to ask.