You are in charge for any usage and any injury you can cause and specially to yourself.
Candy UK and Hoover France didn’t wanted to send me schematics but I finally found where problem was. I baught them for nothing on LEBONCOIN, french used online maket. Seems to be same brand as Hoover or rosiere RVI 469 MM
Useful theory of operation for inductive cooking : AND9166-D
Because relay is back off and because you need current in coil to detect if pan is present or not. It is normal that pan was never detected.
I measured voltage drop from logic stuff power supply and when relay (9v) is switched everything drop. So I removed the dual Coil used to switch 220 DC to 12 V and 5V, and applied 13V and 7 V then this was regulated as usual on the PCB card.
After that everything worked well as expected. So I knew my issue cam from this part !
The main issue was capacitor in the tiny supply used for standby power. I Changed the two 400V 10uF capacitor and all around regulator (rounded with red below).