electrical problems and ecu (won't start; cluster going crazy even with key out)

[avguy]

.... This all started with what I thought was a bad alternator, it killed the battery. ...

Did the charging light come on? If not, there's no reason to think the alt is bad.

In any case, you need to diagnose this with an electrical tool (mulit meter, etc). Anything else is just guesswork and throwing darts.