that seems right. Was the polarity of the barrel jack correct? You need a connector that has the positive pin on the inside of the barrel.
Scapist The Bela said a high frequency howling tone and i plugged the power off, because I was scared it could damage it.
That seems to indicate the power supply was actually OK: if the audio was still running (though maybe shocked by the different power supply), then it means the CPU didn't die.
Can you try gently removing the CTAG cape (ensure you don't bend any pins in the process, see here)? Does it boot that way?
If it doesn't, can you try flashing the latest image on an SD card and boot with that inserted?
If it doesn't boot, try Option 3 here.