Okay so this has to do with my car but I figured it'd fit better in here than in Gearheads.
Anyway, I've gotta remove the factory radio/ cassette deck from these bracket things that mount them to the dash (I need them to mount the new radio I got). They're 2 separate brackets, one on each side of the radio/cassette assembly, and have 4 screws on each side (2 into the radio, 2 into the deck).
These damn screws just won't budge, not one bit, and until I can get them out my radio is put in place with duct tape.

TL/DR:
How do I remove screws that wont turn?

And normally I wouldn't make a whole thread about something like this, but when I can't put into words how stuck these things are, I've never seen anything like it. Flame if you will but I'm getting desperate here.

post this in gearheads.

Ok so I assume youre taking out the factory double din sized head unit and installing a single din aftermarket unit. You need the brackets that bolt to the head unit and allow it to be bolted to the dash.
I hope you still have the screws that came in your aftermarket head unit packaging. Ive found that most factory screws dont like to be threaded into aftermarket head units. Theyre a different thread. Grind the old screws off your stock head unit and install it using new screws. Problem solved. You should probably try a fine thread rather than a coarse thread.

Pics would be quite useful...

USe pliers?

Are you sure you're turning them the right way? ;)

Have you already stripped the screws or what? & are they phillips-head or flat?

I the screw heads aren't recessed into the bracket, and you have a dremel tool with a thin cutoff wheel, you can try to carefully cut a new slot for a flathead bit to fit into. Make sure you cut the slot so that the sides are straight up & down, and use a flathead bit that isn't tapered at the very end so that it doesn't try to slip out as you're twisting it.

Or if you know you'll never want to put the stock radio back in (like if you wanted to sell your car) you could just go ahead and use the dremel to cut the heads off.

1) try using a manual screwdriver, if you've been using a power drill

2) try the other way (seriously. Even if you KNOW they are normal screws, sometimes if you tighten them down a little bit it will "crack" the rust/binding off a bit. Also, the automaker might have sneakily put in left-hand screws)

3) Screw extractors:
http://www.qwikfast.co.uk/catalogue/images/silvscrewextractda70.jpg

Yep I think im going to have to end up buying a dremel to cut the screw heads off.
A couple of them are stripped, and if I drilled slots for a flathead I'm pretty sure I'd end up breaking the screwdriver before I turned these. Maybe they're put in with some kind of adhesive or something?

Yeah pretty much, except the radio is mounted to a dash kit which bolts to the brackets, which then bolt to the dash.
I figure I need a big ass grinding wheel or something to grind the screw heads off?

a dremel with a regular cut off wheel should do just fine.

A dremel cutoff wheel will cut damn near anything. Just wear your safety goggles...

Drill the fuckers out. Be a man!

fucking this ^

Ive had one of those break and fly into my safety glasses and forehead. I have a nice little scar from it.

fucking this ^

Ive had one of those break and fly into my safety glasses and forehead. I have a nice little scar from it.

I had one break off and come inches from my jugular, that was scary as fuck.

I had one break off and come inches from my jugular, that was scary as fuck.
When an angle grinder disc breaks up...that's scary. I had part of a wheel punch through my wooden shed roof.

...and that (among other things) is why I own a full-face shield.

They don't have a hex head around the outside so you could use a socket, do they?