Gen 3 2012 Prius, got low key-fob battery warning, changed it in both my key-fobs, the Lock & Key shop guy explained something about pushing both fob buttons while near the Start button. What is this? I need a better explanation. Drivers Manual is no help.
I own a 2012 Prius. I've changed my keyfob battery so many times now and I have never had to do anything extra. Go take the keyfob for a test. It should work just fine. Unless you replaced not just the battery but the whole keyfob?
Just drive it. I've replaced my fob batteries several times also and never had to do anything but go drive.
Check that the batteries were not installed upside down... Replacing the fob batteries should not affect how the fob operates...