Our Bosch fan oven HBN560550B/02 has a failed board 491537 – I believe it shorted out tracks when a bulb blew – sounds unlikely but the board is beyond repair – Does anyone have a working used one? The error code Er:4 is also showing – could this have caused a temp sensor failure too? I am reluctant to fit pay for and fit a new board only to have it destroyed – any help would be welcome