There is no connecting an external monitor to it unfortunately.
The screen issues, even if not visibly cracked, indicate internal lcd panel damage.
The electronics inside are designed only to drive the built in panel (screen) there is no video output. Even if there were, the only utility of the tv at that point would be as a tuner, for use with an antenna. You can buy a standalone tuner box for about $30 to use with a monitor+speakers, if that is what you want as an alternative to replacing the tv. If you are using a cable/satellite box or other external input, then the tv has no purpose at all, you could hook a monitor directly to such a device without needing the tv.
There are no video output ports though, only internal ribbon cables from several boards that address video signals to the built in screen.
You can certainly part it out, but for a 2008 vizio product it is already about 3 times its service life so the board inside have little value. Personally, I'd replace the tv entirely at this point, it has served its life and value several times over and isn't worth trying to salvage.
If you'd like info on that tuner I mentioned though, just let me know.
Best regards, ***** ***** for the news,