Your problem isn't a power issue at this point if you are getting snow on the TV. The first thing you should do is visit this link
and input your address. This will give you a listing of the over the air channels you MIGHT be able to receive in your location. The channels that come up in green are your best chances for getting reception. Then click on some of the FOUR DIGIT channel names that come up in green, for example, your local WNBC, WCBS, CFOX, etc... You will get some technical information that pops up underneath but you are only looking for one thing, the compass heading. It won't actually SAY compass heading, rathr it will say something like W for west, NNE for north northeast, SSW for south southwest, etc.... These are the locations that you need to point your TV antennae to in order to get reception. Be warned that just because it says you CAN receive the channel where you are, it doesn't necessarily mean you WILL get that channel because of any obstructions between you and the broadcast antennae such as buildings, mountains, trees, etc.. This will work for you.
You can completely skip this paragraph if it sounds too technical.
If you want to take it one step further, there's a number parenthesis immediately following the compass heading so that the whole thing will read like "E (90)." The 90 is actually giving you a much better compass heading to point the antennae to. A compass has 360 degrees, just like a circle. Imagine a clock in your head and imagine a compass. North is at 12 o'clock and also gets a compass heading of 0. East is at 3 o'clock and gets a compass heading of 90. South is at 6 o'clock and gets a compass heading of 180. West is at 9 o'clock and gets a compass heading of 270. Are you following me so far? :-) Anyway, you might get a TV listing that says something like E (80). That might confuse you because you know that East should be 90, but given your location, the TV station broadcast antennae isn't exactly East of you, it's actually East with an ever so slight north direction. This paragraph isn't necessary to get channels but it could help by giving a more precise location to point your antennae.
Your next step is to go into your camper and look for the following receptacle.
What you want to do is press that little black button on it so that a little green light lights up right next to it. You want the green light to be ON. Then you need to run a TV cable from the receptacle to your actual TV. This will connect your TV to the roof antennae.
Next up, raise the TV antennae on your camper. Once it's up, you can pull down the dial on it to rotate the antennae. I'm assuming your antennae looks like this.
If so, the side you are looking at is the side you want pointing towards the broadcast antennae. The side with the wiring should be pointing in the OPPOSITE direction of where you want to get the signal from. Simply turn the dial in the camper so that the antennae faces the correct position.
They also make a VERY easy attachment that you can install on your antennae that will increase it's range. It will make your TV antennae sort of resemble a TV antennae you might have had on your house years ago. Here's a picture.
That little attachment thing points in the direction that you want to get a TV signal from. You don't need this thing, but perhaps it helps in understanding what direction you need to point your antennae.
Finally, go in your camper and turn the TV on. Hopefully you see a snowy picture. Grab the remote for the TV and hit the menu (or possibly setup) button on it. I don't know your TV so I can't say for sure. Hopefully you'll get some settings on the TV screen. Scroll through the settings until you reach the "channel" setting and then select it. Hopefully you're at a screen that lists signal type. Make sure it says "air" and not cable. Then scroll down to the setting that says something like execute, or auto program or something along those lines. Select it and sit back for a few minutes as your TV searches for the channels it will receive. It could take 5 minutes or so but once it's done, you should have TV.