So I assembled the "blink torture" circuit, and continued trying to bias that poor MOSFET that I had heated to 400°C a few times.

At first, I was trying to combine high negative gate voltage and heat, but that appeared to only further damage the already half-killed mosfet.

Then I stopped heating it, and just cranked the voltage up and up. After passing through a few intermittent shorts somewhere around negative 30-35 V, I eventually arrived to -39 V. Cranking it higher caused more intermittent shorts, and while I was trying to penetrate them, I noticed that the LED started to blink brighter.

So, I set the voltage to -39 V, and waited. A few minutes later I was the happiest person on Earth, because I saw a gradual drop of gate threshold voltage. It was slow, but it was certainly happening!

After about half an hour, I got to the point where the mosfet was conducting a little bit at zero voltage on gate!

At that point, I stopped the process, and left it alone for a while, to test, how permanent is the biasing. The biasing did revert to some extent, so the transistor was again non-conducting at zero Vg, but the threshold voltage was still very low.

Then, I've set it up for further biasing. It was progressing slowly... and then the transistor decided to die. A high leakage from gate to source appeared, and I couldn't get it to vanish. Eventually I converted that leakage into a dead shorted completely killed MOSFET.

But the concept was proven! Now on to a fresh MOSFET!