Laserjet M480f - dead and IOD error

[DaIceMan]

I have a M480f that suddenly died (it's just over 2 years old) - it powers on albeit with a black LCD, goes through the toner init process but then just sits there. No Ethernet nor USB signs of life. I opened the side and checked if the MMC module was correctly seated (they are pressure placed on a connector on the main formatter pcb and can sometimes get knocked off if the printer is subjected to hard hits or transport) but everything looked fine. After some fiddling I found out that it's not totally dead: if I unplug the IOD board the LCD does activate and shows a 90.x error compaining it can't detect it obviously. So something is still partially working, the screen works and the touch does an so do the diag tests in the service menu which you can access with a numeric password (12048020 for this model). The EMMC tests ok and so do some other tests. When I plug the IOD connector back the printer does the same, blank screen (black) and does nothing apart from initial INIT. I removed the IOD pcb and unsoldered the 8 pin SOIC 256kbit EEPROM with my programmer and it read fine, I read it back several times and the reads were all consistent. I have no way of checking if the data I read is of course congruent and not corrupted in some way but I have no reason to believe a M24256-BW EEPROM with 4Million write cycles MTBF would suddenly die just being READ in such little time. Furthermore if there would be some corruption I'm sure there is some kind of IOD data validation in the device firmware which would report it being corrupted. I suspect a more convolute problem after the IOD has been read during the initial INIT, but this is speculation. I'd like to know if there is anything else I can try to pinpoint the issue or I should just scrap the device, which would be a pity as it's just as new.