Our power flickered, then went out about a month ago and our GE profile range didn't like it. I get the f640 code, no other codes. It was hard to find what that even meant. I found a service manual and it stated that f640 code was the main logic board and bridge board weren't communicating. I replaced the main logic board, bridge board and the main relay board, the rpsm. I'm still getting the f640 code after all those new boards. I spent about 600 bucks now and I'm frustrated with this POS range. I'm thinking about replacing the daughter relay next. I could have bought a new range with what I'm spending replacing these boards. What am I doing wrong? Thanks.