Thomas Widmaier

You can try using a shim on the side of the contacts. Try some thin stiff plastics from a binder or so and cut a stripe as wide as the sim. Try inserting it carefully between sim card and contacts. Maby this avoids the contacts getting stuck on Sim or the frame. Good luck.

@Dumbo Great it worked. I added the transformer model number. Can you add the thermal image yourself or upload it someewhere, because I cannot post an email here.

Measure if there is any short circuit to ground with resistance or continuity mode around the resistor that gets hot.

Maby the CCFL Tube or wire is shorted ?

High pitched noise is probably the resonance of a coil either the transformer or another inductor of the swtiching regulator circuit.

You could try and measure the inductance / resistance of the transformer (desolder first) and check if they match very closely.

I guess it´s not 4 but 6 screws and the two of them are hidden under some cover...

Ripping out the threads is not the designed solution.