I just turned the tv on, and there is blue snow over the picture. The sound will not turn down, and I can't get the channel to change. It also takes much longer to turn on and off.

Check and replace its tuner. If you wish to get some details; visit the site linked here. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/

tried to hooked up with an air antenna. if you can not get any channel and just a white raster or snow, it could be the tuner get fried.

Can you still turn it on?
If so, does it stay on with sound?

If the sound is ok and the picture is blue (even when changing channels, inputs, etc.) the lamp may have gone out.

Can you see the TV menu when you press the menu button on the remote or TV?

is it snow on screen? if so tuner  problems. rca had recall on tuners on some models bad solder connections in tuner

Two things may be at play here. The tv might be only programmed for reception on channel 2 and will need to be re programmed to receive other channels.
Also try some basic troubleshooting on the remotes. Start with the remote that came with the tv. Replace the batteries try the "MENU" button. If you can get into the menu try to "autoprogram" the TV

It sounds like a defective tuner or a IF module as well. It may also be a defective capacitor(s) or cold solder joints inside the tuner circuitry. I woud suggest to use a VCR or a TV convertor connected to an Audio/video input to change channels instead of fixing it.
Good Luck.

Bad primary tuner==can be replaced,or==by-pass by using video inputs.

My shop had this problem yesterday. We had to change the DMD to correct it. One of the data lines was being drawn down intermitently. This doesn't eliminate the digital PCB, but, we have seen the DMD do this more than a digital. You should have an authorized shop do the repair. Contact Samsung at 1-800-SAMSUNG or contact by email: http://samsung.com/ContactUs/ContactUs.htm Hope this helps.

sounds like 2 different problems here. first problem sounds tuner related. second sounds convergence related. third issue (cost effective to repair ?) at this point i would replace the set. i hope this helps

Make sure the ant. input switch didnt change and check the ant. connections If that dosent work sounds like a defective tuner.