Digitizer on iPad 3 was not working—no touch sensitivity at all.
Bought new digitizer. Opened case with iOpener and guitar picks. Opened latches on ZIF connectors to release ribbon cables of digitizer and LCD screen. When replacing new digitizer ribbon cable, which comes in two parts, one part would not fit into ZIF (Zero Insertion Force) connector no matter how strong the force. I used the old digitizer cable to test this -- couldn't get the old digitizer cable back. I conjecture that this ZIF was defective in some way (other half of digitizer cable fit just fine). Then I tried to replace the LCD ribbon cable. It went into its ZIF connector with a little force but destroyed the connector leaving little gold needles (ex-connector pins) on top the logic board.
I enjoyed this experience because I learned a lot about the iPad (even thought now it's an expensive paperweight) and I recommend that you warn first-time digitizer replacers about the possible fragility and possible malfunction of these ZIF connectors. I suspect that the reason my original digitizer failed was not the fault of the digitizer itself but because quality control on ZIF connector was lax and the digitizer was only barely connected through a defective ZIF connector. As to why the LCD ZIF connector shattered upon insertion, I can only conclude that the bucket of ZIF connectors the Chinese worker used to assemble this iPad should have been thrown away—but wasn't.
Broke two ZIF connectors-- one digitizer and one LCD.
Warn your fixers about fragility of ZIF connectors.