I love the F5S, there so basic you can't go wrong. Unfortunately there so many clone on the market, which kills them. I had no problem ever with mine.
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I feel that when People Brick the boxes, they don't delete the channel list and there just adding more Data and basically the box cant take all the DATA and goes into flash mode for the most part.
I also think now with the DIM 8, that with a Box being original it will flash, not compared to the clones which rarely flash.
I had over 20 boxes send to me in the last Month, mostly on DIM 8 and all have flashed and where real boxes.