I gave a motherboard circuit board to local a repairing professional. He traced and soldered some chips but it is not still working and advised to show motherboard to manufacturer service center.
But my motherboard now has yellow stains after marks of soldering or maybe soldering flux paste. I am attaching photographs of the soldering marks for your reference.
Before showing to service center I want to clean those yellow marks as some service center technicians make excuses if it has been soldered by local technicians - they may refuse to even touch or find the problem.
I have tried to clean by isopropyl alcohol, but the marks are still there.
Can someone advise or suggest how and by which chemical can I clean the yellow after marks solder or solder flux paste?