It's weird that you got both a new mainboard and a new i7 board and it seems like those STILL can't communicate with anything... so you can't even do what Pool Clown suggested.
I may be missing something glaringly obvious, but I'm wondering (and I think Jim alluded to this too) if connecting the heater smoked everything on your comm bus. If it did, could it have smoked something bad enough that the new boards also got smoked when you connected them? I've never seen that happen before but it's possible.
I'm not clear on whether you tried the whole "connect the screenlogic only" test with your OLD boards or your NEW boards... we want to test whether the screenlogic (screenlogic protocol adapter) alone can talk to the new i7 that's connected to the new outdoor mainboard, and then go from there. If you have a wireless link for your screen logic lets remove that as well.
So I'd do the following:
1. shut off the power and take a picture of and/or label your i7 setup so you know which wires go where
2. disconnect everything that's plugged into your i7 board
3. if the new i7 and the new mainboard are not installed, swap them in now
4. reconnect only the power and temp sensors to your new i7 (that's now on your new mainboard) - don't connect any valves, relays, or heaters. (If you don't reconnect the temp sensors, depending on your firmware the controller will throw a fit, an error, and/or go into freeze mode)
5. if you have a wireless link for your screenlogic - disconnect your screenlogic from it and connect the screenlogic directly to the comm port and plug it into your network... this may require some creative extension cord/cat5 cable business
6. turn on the system and see if screenlogic can connect
If that STILL doesn't work then my best guess is either the screenlogic protocol adapter or the new mainboard has a bad comm chip.
I don't want you to spend any more money on new boards... Pentair led you astray with the i7 and I may have too, thinking the original mainboard was bad.
Let us know what happens and we'll take it from there,
Tom