Surface won't charge - Battery OK - Charger OK

Hello.

I have facing an issue with my surface pro 4.

Because of a faulty charger (probably?), the surface stopped charging.

I tried to charge the surface with another charger dock). The dock itself is fine (working on another tablet), but still wont charger on the broken surface. No light.

The battery of the surface also is fine ( I can still run the surface on it, few % left).

Seemingly its the circuitry that brings power from the charger to the circuit board/battery that suffered a short or something.

Are there guides on how to diagnostic and or repair this kind of failure ?

Thx