Mystery: No dashbard lights and it's not fuses

I have a 2011 Corolla, which is paid for, and when I got into vehicle and turned ignition, I heard a pop sound, radio went out for couple seconds, came back on, but now I do not have dashlights. I have head and tail lights. Radio works as does back light of radio, but when I put on headlights, the back light of radio goes out. My mechanic can't figure it out and says it's NOT the fuses; they are all fine. Does someone know what this is happening and how I can be able to see my dashboard at night? thank you!
I ended up picking up my vehicle without it being fixed and it was suggested to me to take it to the Toyota dealer, which I didn't want to, just for the cost, my vehicle is 8 years old and since they have new management, I don't trust them. It seems they're out to make a buck and not looking out what is best for the customer.