You have a problem with the charging system, probably a bad alternator.
Take the blazer to a local autozone to have the battery tested for FREE! but the blazer would not start if it sat for a couple days or so. also it would start hard, but once it started it would run fine.
Have the battery and/or starter tested for free at your local auto parts store.
I would recommend 500 minimum.
That would tend to indicate that the alternator was not charging the battery for that interval.
Yes
it indicates that the alternator is not functioning sufficiently to keep the battery charged.
The check engine light would come on and the code stored would refer to a bad cat.
yes, 82-93 are the same besides grill design
the 1996 and 1997 are the same and would not work in your 2000 straight from GM
That would be the 4L60E
It could also be a corroded connection, the fusable link or the keyswitch.
i would say its probably the security system. watch and see if the security light is flashing. if it is leave the key in the on position for ten minutes and watch the light when it goes out the vehicle should start.