First, check to make sure the battery is O.k. with a volt meter or DMM. Make sure the voltage is above what is engraved on the battery. If its close or below, replace the battery. And make sure you install it correctly.
If that doesn't work, remove the battery and press every button on the remote, one at a time, holding each for a couple of seconds. Correctly install the battery and give that a try.
You're correct about needing to hit the Pre button, I've heard that sometimes you have to press it each time before you try to use it, but I think that was just the first ones, mine isn't like that.
Hope this helps
R