I didn't check the tv due to the fact it was a somewhat common occurrence for it to turn on at random, even if the timing and the manner of it turning on and off rapidly was bizarre. When I check there was absolutely nothing wrong or disturbed other than a door that was locked became unlocked.
I have a very. Very. Very. Bad phobia of paranormal things. I'm not scared of much but anything that comes off as paranormal makes my knees shake. Hence why I didn't check the house at the time. It also came from a locked room that has no way in. No windows and an electric garage door that is extremely loud. Not to mention I was sitting 5 feet from the garage door. So I would have clearly heard any intrusion via the garage. As well as my nana had told me to leave if anything like that were to continue happening. Please explain to me how the dogs strange behaviour as well can be due to pests

Your dogs are reacting to an animal that's in/around the house that shouldn't be in/around the house.

You're looking for patterns where there are none. You see your dog acting in a weird way, and you go looking for extra information to explain why. You're predisposed to believing it's paranormal, so you look for a paranormal explanation. You see the dog is looking in the general direction of a picture of your dead grandpa and make a conjecture they're related. You then experience an event that seems unexplained and seek to attribute it to something just previous to rationalize it.

Now let's fill this in with a few more details from your event. You think your grandfather would be a benevolent ghost, correct? And if you truly believe your dogs are detecting the paranormal, then the fact that your dog was "staring" at a picture of your granddad would have implied you thought the paranormal event was your granddad. Then the event you experience afterwards is perceived from you as hostile. This doesn't match up with the previous assumption that your granddad would be benevolent. Yet there's no indication that it should be anything other that your granddad based on how you're assuming things. So your thought process to justify this paranormal event leads to a conclusion that does not follow.

This makes me believe you're not experiencing anything paranormal, and are instead looking for information to confirm your belief, and ignoring any relevant information that would prove you otherwise. Damned be the fact your conclusion doesn't follow from your evidence, you feel a loose connection between them and are now convinced that it's right because of this weak connection.