What's wrong with these defective EDC modules that some of us have?

[RedCardinal]

After 2 years I finally discovered that I needed to replace the EDC module to stop my mysterious parasitic drain. The key for me was realizing that my start or ignition button light stays on, evidently forever, when the module is acting up.

Question: So what's the problem with these things? It's not the programming, so its either a failing onboard chip or a design flaw maybe?

I have a nice, shiny, new-looking one right here in front of me from my car - it does not work correctly - and I replaced it with one that has 4x the mileage and looks beat up, but doesn't drain the battery.