On nissans it is normal to sometimes see the key symbol or a message saying "service electrical system" since the vehicle was started without a valid keyfob in the vehicle communicating wirelessly. If the message goes away after takeover, everything is fine.
If the message does not go away after takeover then there's an issue. You all say everything was removed and put back to OEM and the light is still on, this will indicate that there is an issue in the vehicle itself,
If the vehicle went back to normal after the removal of the evo system then, the issue may lie with the remote start system.