Welcome to ETO, B-in-N!
Sadly, my guess it that without any obvious diode protection, you've managed to cross polarize a lot of parts (especially micro C's) that do not tolerate that situation at all. What that also means is that replacing SMD devices is probably well beyond your current expertise.
In short, toss the unit, get another one and learn from this particular mistake. If you stick with the hobby, this will just be your first mistake, trust me ... !