Alright. Well, I tried but I have really used transistors or MOSFETs since college. Those diagrams you had looked like they made sense to me, so the only thing I could think of is the transistors are expecting a different voltage from what the batteries are providing. But, it looks like some other people have responded that are much more familiar with transistors, good luck! I hope you get this working in time

Any possibility that you have some small solid state relays sitting around? Power to the coil can be the tripwire, so when that is cut and the relay closes the NC contacts it turns on the speaker

I am so drunk right now I thought you were looking for a power supply for Electronic Dance Music. Let me check back in like 10 hours

Update: I am back and I’m sober, and I know nothing about this.

For this use, definitely stay away from Maglites or other camping or survival type of flashlights. The cheap children’s flashlights usually have plastic housings that should be easy to open, and you can always put rechargeable batteries in them

Edit: cheap plastic flashlights like these. Excuse the Amazon link, it’s just the first one I found https://www.amazon.com/Eveready-Flashlight-Multi-Pack-Emergencies-Batteries/dp/B08YM5S28F/

Good news! Any thing can be dismantled if you are determined. Flashlights aren’t too complicated either. So yeah, any flashlight should work, and just start ripping it apart

Might be worth your time to email Panic and see if they can send a replacement screen if you haven’t tried that yet

You have a pretty good list already. There are definitely still electronic component kits out there that are a handful of resistors, capacitors, and transistors of different values and some LEDs. You can also look at the parts in these kits and order them yourself from a place like Digi-key or Mouser, not sure what is available to you. It might save you a couple of bucks.

You probably don’t need a variable power supply, unless you really want one. But you should be fine with a 2 or 3 AA battery holder that has some wire leads you can plug into the breadboard. 10k Ohm potentiometers are the most common and the only kind I think I used in school. You can also look into logic gates (NOT, AND, OR, NAND, XOR) to start getting into the digital side of electronics without a microcontroller. Logic gates are the building blocks behind modern computers. There are IC chips that fit into breadboards in the 74HC Series.