Aalong,
While your wrestling in the dash, take the time to inspect proper continuity of all fuse/relay connections from behind the relay block to the front contacts. I've been having an issue with my left high beam and it turned out to be an open trace/cold solder joint inside the unit. You'll have to label each single and multi-wire connector (take pics and draw a diagram) prior to removal. It's a job but doable if your not afraid of wires.
This is my spare unit that was purchased strictly for research/testing purposes. Unfortunately, it also has a couple opens inside. I'm not sure if PP sells a new unit but they're available on online. As a couple of other have mentioned, it may be advantageous if original equipment was reinstalled...