In an last attempt to save your Pi, you can try to bypass the fried onboard regulator with an external 3.3v regulation circuit.
I haven't tried this myself, but this is the type of module I mean:
https://usa.banggood.com/DC-DC-3_3V-3A- ... ehouse=CN
Edit: This specific module would require soldering. With this module, you would hook up the wires to your Pi like this:
On module - - on Pi
"In+" - - - - - - - - +5V
"In-" - - - - - - - - GND
"Out+" - - - - - - - 3.3V
"Out-" - - - - - - - GND