Just wanted to update on the MBP situation.
After I got my MBP back from PowerOn, I played with it for a few days still did not see the so called "flickering sreen" symptom.
I thought I'd give Gazelle a try and put in a request for quotion, and based on the condition of my MBP, I got $433.00. I liked the quote so I dropped it off at Fedex, and it was professionally packed and sent to Gazelle. Within days, the staff concluded the condition was as described and sent me a check of $433.00. I feel great and validated as a Mac user.
PowerOn might hook you in with higher quote, they definitely do not always honor the quot. I did not "LIE" to PowerOn as some user suggested. That particular user was just lucky with her iPad 3rd G sale.
I'm sure Gazelle is a more well known company that recycles Apple product than PowerOn. If Gazelle staff deemed the condition of my MBP was worth 433.00, then its condition must be far better than "Defective LCD Dispay". My conclusion is that POWERON IS ******** WITH OUR USED PRODUCT.
My sincere suggestion is to try companies other than PowerOn. If so many people contributed a thread, there is a reason. Where there is smoke, there is fire.
Maybe you get lucky this time. You will get screwed down the road.