Wf501b with P7 stopped working

I had a Wf501b with a P7 from DX since some years, it worked till today.
Normally I never used this Light anymore but today I wanted to charge the trustfire flames in it so I put a Panasonic in it and played around.
After 5minutes it stopped working….
So I measured voltage on the Led 3.25V, I desoldered the pill and checked the LED itself -> nothing but a infinite resistor…

So was that the common heat issue or what? I never optimized it because I thought that it won’t break.
Or is it a bad driver?

Any hints what to do? Has someone ever dedomed a P7 to check the 4 LEDs themself?

I have only a U3 and 3A driver and a xre laying around, the XML is too much. But I could try the xre with the stock driver?