Easy and Quick Thermal Simulation of PCBs

I could NOT get the Open-Source Thermal Simulation of PCBs technique to work with my 4-layer PCB board at all, even after spending some days on it. To make things worse, I was NOT able to get useful debugging feedback from the involved patchy toolchain. Getting access to the TRM software by ADAM Research turned out to be a sort of very bureaucratic and slow process - I never ended up using it.