Look up "redsn0w" and you should be able to do this on your own. There are a lot of guides online if you look hard enough. http://www.geek.com/articles/mobile/how-to-jailbreak-ios-5-0-1-on-windows-or-mac-20111227/ *NOTE: Apple does not condone "jail-breaking" your iOS device.*
You need a small bent paperclip (or the proper tool) to open the slot for the SIM card on the phone. You should then be able to pull the existing SIM card out, or shine a flashlight in and find out what may be blocking it. Note: If this is a Verizon iPhone 3GS, it is likely that it does not use a SIM card. Verizon is notorious for not using a SIM card on past models.
Can you connect back to the original TV you were using, or a higher resolution HDTV? I had this problem as well a while back, and I found I had to do multiple system resets and power on/off etc. Really a pain in the arse. If it is the older model, try "oldtukey03"'s suggestion with using the composite cable temporarily; since this is an analog output it should work regardless. HDMI is digital output that requires Link Protection Protocol on both ends of communication. Regards, -- Morris
Re-install your old operating system on top of the Mac OSX 10.8 Mountain Lion Developer Preview. It's called "experimental" for a reason. Also, I am very curious as to whether your computer met the minimum requirements for the install? Sorry the hear the bad news... Regards, -- Morris
Hello Andrea, Your MacBook is not turning on because the computer is failing the Hardware Check when it runs at initial start-up. You must replace the iSight camera cable before it will function again. Sorry to hear the bad news. Regards, -- Morris