OK, firstly, calm down. The main thing is the car should still be driveable, because the immobilizer is a separate box so you won't have fried that. The cluster is an independent unit. They're not even coded to the ECU. On other VW's, the immobilizer is built-in to the cluster. If you had this issue on one of those, then I'd be worried. You should be able to start it and drive it etc, so that's the main thing (after all, it's a car, driving is it's primary function, regardless of whether the mileage is shown), however, let's work logically and see if we can sort it. Secondly, I'm going to take a punt and say draining the battery did not kill your cluster. Even starting your car with low battery shouldn't kill your cluster. I've had two Lupo's. In my first, I drained the battery by leaving the radio on, which meant when I turned the key, I had the same issue as you, the car cranked but not enough juice to start it, the cluster scrambled and went off etc. However, once reconnected to a slave battery, it came straight back and remained till the day it went. Volkswagen spend millions in research and development, imagine if everytime someone let their battery get a bit flat this happened? They're not going to make such a trivial mistake. They will ensure that the mileage, and service values are all stored in a non-volatile memory bank and ensure that the circuit can withstand repeated losses of electricity, dangerously high currents, and probably significantly low currents (as to replicate the slow failure of a battery). Similarly, on my current Lupo (a diesel), I walked out on a very cold morning once and forgot to let the glow plugs sit for a few seconds. I went straight to crank it, and the starter motor turned the engine over but wasn't able to start the car and the electrical spike again caused the dials the scramble (and the loss of all my radio stations grr). The car immediately started on the second go and the dials remain fine to this day. So with that in mind, I'm going to say that this has been potentially caused by a short, perhaps in your sub wiring or the method you fitted it, so make sure you go back and check that before we go any further. Also, without trying to sound mean, if you're mucking around with live wiring, as opposed to disconnecting the negative terminal first, you always run the risk of something like this. Hell, you run the risk of damaging your ECU doing that. You said you bump started it, so I assume the car does start right? We've all ****ed about electrically without disconnecting the battery first, don't get me wrong, but you should always ensure you're not messing about with live wires. Say you're splicing in a boot light or remote central locking as per my how to's, you should splice the respective live wires first, especially a constant live. Regardless of accessory, you should always connect the negative/earth last!! It sounds like your sub is permanently live which means if you didn't disconnect the earth/negative, you've been playing with live wiring. The reason that's dangerous is it only takes a wrench or piece of conductive material to touch the car body and you have a huge short, which can blow all sorts of things: ECU, clusters(?), bulbs, radio... it's just better to be safe than sorry. Anyway, lecture aside let's see what we can do, follow these steps. I'll recount the steps we followed to bring back a different digital dash. It wasn't a Volkswagen, but hopefully this will help, if it doesn't, you might need to get it recoded or even replace with a new one from fleabay (personally I'd go for the second). Disconnect the negative terminal from the battery and leave for 5-10 minutes. Reconnect the negative terminal from the battery and start the car. Drive it for at least 1 mile. In fact, I suggest driving it for about 4 or 5 so you can be sure that the mileage indicator is being incremented (it may immediately come back at this point, however it may not, do not be alarmed if it doesn't). Disconnect the negative terminal for another 5 minutes. Report back with the results. Worst case scenario, it doesn't work. Best case scenario it does. Middle case scenario, it tries to increment a corrupted memory bank and returns an exception which results with the mileage either going incredibly high (999999) or incredibly low (0).
Oh dear... Which head unit were you using when they popped? OEM? I've heard of a single speaker blowing but your entire right hand side, at the same time, that kind of sounds a bit odd. Have you popped the door cards off and actually had a look at the speakers to make sure it isn't something else? You might whip the door cards off and find two aftermarket speakers that have been wired in with twist and tape or something stupid like that. If you want to test the speakers, take the door card off, check the speaker using a battery. When you connect a speaker to an AA battery, you should hear a feint click. It's a perfectly acceptable way of testing speakers and more importantly, speaker wiring. If the speaker pops when you connect it to a battery, then your fault is with your wiring and you've bought a set of speakers for nothing lol.
It's a well known fact that volume isn't what blows speakers. It's frequencies. As you say, if you push your head unit too much to the point that it begins to clip, the volume will not blow them, but the extraneous frequencies from the head unit. Personally, I suggest changing both. Get a better head unit with a higher output (7W is mickey mouse) and get a better set of speakers to go with it. Winner! Edit: You don't necessarily need an amp to get good sound Just my 2p