I have same issue, and today requested Nokia to fix it. DHL came to my home to pickup the phone in a 30 min. I was surprised how fast it working, so until now have Nokia great support.
Lets see what the solution are from Nokia about yellow screen...
Me too, my screen very warm and somtime it become pinkish, i don't know how to fix this problem.
Send your phone back to Nokia. Go into their homepage nokia.dk then select below.