Quoted from pete_d:Components can fail in a variety of ways. What you're looking for is the component behaving differently than it would normally. For a resistor, that will generally mean very low resistance (less than 1 ohm), an open circuit (no continuity at all), or as you say, resistance not the same as what the resistor should be. But there are other types of components, and they have different failure modes.
You can usually measure a resistor's resistance in-circuit, but other components often can't be directly tested while they are connected to the circuit because of interactions with other components they are connected to. But even so, you can do basic continuity checking, and even diode tests (which are useful for both transistors and regular diodes) usually work okay, with some exceptions. Those kinds of tests will allow you to find components that have shorted internally, one common mode of failure (and the likely mode, if you also have overheated components on the board).
If you like, you can also take a high-resolution, in-focus photo of both sides of the board and post it here. An extra set of eyes never hurts.
After buying longer alligator clips I did some testing and the signals, board, and sub all work. The problem was that one of the connections failed a continuity test so I’ll need to buy a new wire harness for that connection. Anyway thanks for the help luckily it wasn’t something major.