I don't know if this will help, but I had a similar problem, or maybe even the same issue... When my switch box is set for both TVs and the DVD player to be on the correct (and same) "signal source", my bedroom TV will show a blue screen IF my remote has the wrong "input" selected. Mine is an RCA, and the remote has a button labeled "input", but it could be called something else on yours. When I select ch 3, I get the same signal as the front, the words "CATV 3" appears momentarily, and all is good. If I hit the "input" button it will switch to a blue screen with the word "front", hit it again and the word changes to "video", also with the blue screen. The really odd thing about it is that the rear TV needs the "CATV 3" screen selected whether the incoming signal is cable, satellite or DVD!! It seems that the TV doesn't care what it's getting from the switch box, as long as my remote selects the correct screen. It's been like this from the beginning, 2 1/2 years now. So, I would try playing around with your remote using any button that is an unknown quantity, especially if it sounds anything like display, input, select, or things like that. If your other options work, like playing a DVD switched from the front TV, then it seems that your switch box is doing its job. I'm pretty sure your problem is with your remote settings.... I know how frustrated I was with a blue screen! Best of luck!
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