Maybe check the Detailer first before you attempt the steamer/hairdryer, Sun is okay to do. The thing with the hairdryer or steamer is to have it on low, don't go to close, but if too far away it won't be effective. Move over the area with moderate speed, checking results often such as every 30-60 seconds. Anything like this takes patience. I didn't ask - is the 'ring' a lighter or darker colour, if yes and once the indentation is taken out, a good detailing product over the entire dash may even out the colour. These things are hard to access over the internet. Best of luck to you!