Actually, it's much easier. Once you narrow down the buggy behavior sufficiently in software, you can literally go to the hardware with a voltmeter and measure

Actually, it's much easier. Once you narrow down the buggy behavior sufficiently in software, you can literally go to the hardware with a voltmeter and measure exactly what is vs what should be, identify the offending part directly, and replace it using little more than fingers and a soldering iron. That vs "narrowing" it to a 100+ pin component that does a significant fraction of everything, with replacement being little more than throwing the whole unit away (you did want the newer version anyway, right? good excuse to get it now).