You may have damaged the core diode chambers near the main flux circuitry. These are susceptible to extreme heat whether a dashboard or microwave oven. I would pop the cover off and inspect the board with a copper dioxide view port module.
Poast a pic of what you see so I can diagnose it properly.
There he goes. One of God's own prototypes. A mutant of some kind never even considered for mass production. Too weird to live and too rare to die.