If you read prior replies on this the maker's line is no way back. If you want a hack/workaround you head to hack forums and hope someone will guide you BUT you accept the risk of a brick result and having to replace boards.
Some folk get very upset at the current state of firmware in consumer products.
I have a question about a firmware update file .upd for Sony Bravia LED TV. I updated the firmware with the latest from their site and I want to return to previous original firmware. Can I use HxD program to tweak the process ? Meaning take the original firmware file and change the increment value of the latest installed firmware with a higher number so can I reinstall original firmware?