sioscan "Atomic Clock" instructions?

I just had to replace the batteries on my "sioscan", a basic indoor/outdoor clock/thermometer available at Costco and Target a few years ago.

Since replacing the batteries, it no longer displays the temperature from the outdoor sensor. I remember that there was some specific sequence needed to synchronize them, but I CAN'T remember where I put those instructions!

Does anybody know the trick?

-= Herb .