The 5100/5800 can be very stubborn at times. First off, you're going to have to open the cover and look on the motherboard for the build config sticker. It's a small square with 4 letters. You need to find a build that matches at least the first 3 letters. Next you'll need a buffered jtag (a simple universal or quad won't do).

If you only want to switch from BEV to Dish, try this first...

Open Jkeys 2.1.0, go to 'Flash Programming', next use the pull down (left side) and select flash 2. Then under 'Chip/sector programming' (right side) use drop down and select SA54. Hit erase 4-5 times. Now connect back to sat feed to force the upgrade. If that doesn't work, then you'll need to reflash the whole TSOP. If that's the case, then let me know and I'll walk you thru it.