I see you are talking about video monitor displays. This may not apply but I will put my 2 cents in. I am sure both these methods would be damaging to screens, so just boards. I wouldn't put an lcd or led screen in either an oven or freezer.
Laptop bad video chip repair/reball procedure - wrap board in tin foil, place in oven at ( I think 200 degrees) for ( I think 30 minutes ). Google for correct info.
I remember bringing a couple back to life a few years ago.
Guy at work Googled and found - put it in freezer for X minutes/hours and that was supposed to do the same/similar thing as oven. I basically told him don't believe everything he Googles on the web. He came in the next day and said it worked. He used the laptop for another year.
(maybe Ripleys believe it or not on that one)
Anyway, maybe it's all just urban myth??
Had to share.
Tony