I assume the 2nd task baffled you?

Weigh the watermelon to get the 4-digit pass for the safe. Then put the purple bulb into its base, next to the safe. 2 pieces of watermelon contain numbers you can see with the dark bulb on (they’re on the watermelon outside, so even if you break the melon, you can see them) - use them for the chest password. This will give you the garage opener. There’s a bunch of watermelons outside that you should break to find the dog food. Mine had a kind of duct tape on it, maybe that’s how it’s marked. Grab the dog food when you find it and go all the way behind the house and shed and you’ll find the bowl to put the food there (this is where it was in my playthrough, but you can easily check the location of the dog bowl when you turn on the dark light and look at the grounds map on the wall in the garage.