Dell Optiplex 7040m - black screen, no logo no POST, 3 amber 6 white LED flashing error code repair

Here is a Dell Optiplex 7040m Micro PC that has a black screen, no logo won't POST and a continuous flashing error code of 3 amber and 6 white - the service manual states that error is a failed MNB (Mainboard) and to contact support but further searching says its an Intel Management Engine Timeout error caused by a corrupted ME region in the BIOS, tried bios recovery through USB ports - renamed the original dell bios file on a thumbdrive and powered up with keyboard hitting escape and various other key combos but nothing so went the re-flashing route - the bios chip is an SPI 16MB/128M-bit NOR flash GD25B128CSIG in a SOP8 package - to find the correct bios thats been ME region cleaned search forums/facebook groups/discord/telegram/archive.org/torrents etc and you might find what your looking for...