Prius Smart FOB no longer working as Remote

My smart key fob for a 2008 Prius no longer works as a remote. The

physical key opens the door and when the fob is placed in the slot on the

dash the car starts. I replaced the worn shell and the fob continued to

worked for about 2 months. Then died. I've taken it to an auto locksmith.

Opening the shell they witnessed the red light flashing on the circuit board

when a button was pressed. They tried to reprogram the fob to no avail.

Then they attempted to program a new fob. This also did not work. I was

told it might be a bad fuse in the car. On a chart I located two fuses that

work with the smart system, but both also monitor power for number of

other systems all of which are operating normally. I was told this has to go to

Toyota. Any suggestions?