OldLexusBy

OK, so I'm looking to buy my neighbor's old '96 ES300, so I took it for a test drive today. First, the thing seemed to have a bit of trouble starting, but no big deal. We started driving, and there was a small issue with the tire pressure that we fixed after getting around the block. We started it again, it was warmed up, and it started really easily. Drive around some more, everything's fine. We get it back around, talk a bit, then go to re-park it, and the alarm goes off(possibly relevant?)

Now it won't start, the key starts up the electronics fine, but turning it further results in nothing. No sound, no crank, no turnover, almost as if the car isn't in park.

The battery is new-ish, but jumped just to be sure, and that didn't work. The starter and alternator have both been replaced recently.

Any help?

Edit: so after looking around a little more, we kept charging the battery, and then checked out the purple relay, then reinserted it, and it started fine. If anyone could tell me how to prevent this from happening in the future, I'd be grateful.