Ok, took a printer (Brother MFC-7820N) apart because it fell silent, found all voltages to be there, all crystal oscillators humming, but the DRAM is never accessed. Big fat uC on there, says "Concordia Japan" and the P/N is LJ9899001. No logo. The web shows the usual collection of Asian sources but the datasheet links are always dry.
What company is that? I only know a Concordia university.
I am suspecting a reset because the POR/BOR has always been weak. This doesn't surprise me anymore these days but my last ditch effort before the printer goes lalaland would be to roach on my own reset circuit (that has revived many electronic devices in the past).