Samsung Galaxy S3 unusual problem - Screen inconsistently blacking out and coming back
I am having a strange problem with my Samsung Galaxy S3. It started with colors on screen becoming brighter and brigter and this lasted for 2 days. I restarted my phone few times after everything was OK and after a while the colors started going brigher again until at one point screen became black totaly. Now, when I lock/unlock the phone, screen start of as completely black and slowly the screen comes back to life from top to down, but not fully, maybe to 75% from top and the colors are strange (like 256 color scheme o windows 98). But when I enter the camera app the screen is showing the image on 100% of area of screen, but the colors are still strange.
This incosistency is giving me the problems. I am not sure if the screen is dead and I if I have to replace it. I have not droped my phone nor it was cracked in any other way. I went to mobile shop where I bought it and they say that even though they can not find any damage to the screen it must be broken because "it's not working properly".
I have not found any thread with the same problem, so if some can help me it would be good.