Looks like a capacitor/ choke in your old PSU exploded for some unknown reason, most likely overloading, overheating or voltage spiking.
This failure not only took out your PSU, but most likely your motherboard or GPU together because of a sudden short circuit. Possibly even your RAM chips and CPU.
Test your components on another board or run without RAM, without a GPU, if it does not POST into BIOS, hear for an error sound. If no sound is heard, very likely your motherboard is fried, though less likely it could be your CPU. If it did enter BIOS, your CPU and board is okay, and most likely your GPU is dead.
I dislike to be the bearer of bad news, but something died in your PC.