The connector on the analog board to check is not a yoke connector. It is the connector for the cable which runs between the analog board and logic board. There is only one cable which connects the two, so it is easy to identify. Pin 1, which is the pin by itself (position 2 is blank) should be desoldered and resoldered. I can't guarantee that this is the problem but it usually is in this type of case.

A simple but not perfect test is to slap the machine on the left side while it is turned on. If the screen comes back for a moment, then it's definitely that pin 1.

The failure will not be visible to the naked eye -- at least, not unless you're very skilled at judging solder joints.