well, with a possible water damage all bets are off - the issue might be with multiple modules that are in the vicinity of water path... The fiber optics are not subject to corrosion but the joints and connectors may get moisture and get some deposits lodged in them (which should reduce the signal quality but still, remain operational). The modules still rely on solder joints, components and wires inside the modules, which do not like moisture, as it introduces unwanted electrical passages and as a result, can fry a component...

If there is water damage, I don't think you can get away with fuse tracing... you would need to locate the HUD module and inspect it. Also will apply to radio module... It is possible, that moisture got into the projector of the HUD system, and electricity may have found a new path, and that new path has either fried or shunted the other modules...

Troubleshooting and tracing this kind of problem at a dealer or a audio shop can be cost prohibitive as the cost of labor can skyrocket - depending on your personal skill level, you may consider this troubleshooting yourself...

First, I would start out with the map of the modules and their locations. Then, knowing where the damage to the windshield occured, I would start from the location of moisture penetration and try to locate and trace the path of water.inspect the wiring (metal conductor wires are still part of the car, as power travels through metal, not fiber), check the pins for corrosion... Since may parts in the car are talking to each other, a shorted or corroded pin on one module can wreck a havoc on operation of another module...

how comfortable are you with digging into your dash?