I don't know as this will help but I once had a building with several fairly new Lennox split systems that burned out a few boards. One unit in piticular burned out 3 over about 60 days. I did away with controls and replaced them with old school controls on that unit and never had any more trouble. I installed a device to record and time stamp voltage fluxiations of more than 10 volts at entrance to breaker box which found spikes up to 180 volts. After I persuaded utility company to replace their transformer,didn't have any more trouble. I've never been able to put rhym or reason nor seen anyone else to why boards burn out. Were I faced with another situation like described above and utility company couldn't remedy it I might install a voltage limiter/clipper on 24volt transformer.

To recap. Me and everyone I know usually replace's boards without trying too hard to find cause of burn out if it isn't obiovous.

If the EPROM was damaged then the most likely cause is the power supply voltage exceeded its maximum rating. See if you can measure the DC voltage power supply. There is a good chance the DC rectifier circuit was also damaged. If you can determine the part number of the EPROM I may be able to find out which pins are power and ground and the nominal supply voltage.

Did you have a thunderstorm recently? A lightning strike could cause a voltage spike and damage electronic circuits. This is the reason it is always a good practice to install a surge protector on a furnace installation. I would also follow Klem1's advice about looking into the utility voltage supply and measuring the voltage on the 24 V transformer.

Why wouldn’t you want to have it serviced by a pro rather than replacing expensive parts and risking immediate failure due to burnout with no warranty if something’s wrong that’s above your ability to diagnose and repair?

Sounds like, “Penny smart & pound foolIsh”.

Because I can replace 3 of these boards before they even start the meter and I'm confident I can diagnose and repair this for much less then they do, I am just looking for helpful hints. From what I have seen some of them guess and replace and blame it on something else if it doesn't workout your stuck with the bill for their guess and replace technics at a over inflated cost. So take your penny wise and pound foolish and apply it to your own endeavors.