The hot coin is the only method I could do right now due to lack of tools. But I just don't think it would be the safest as you would be applying a huge amount of heat immediately and directly onto the GPU. One guy in this thread placed a strip of aluminium on the GPU and gradually heated that up with success. I found an old P3 heatsink that might do the trick. I could place that on the GPU and heat it up with a heatgun. That way I'm not directly applying the heat to the GPU itself.