Hi new member here

Hello. I'm riding a klx250 but about to buy a 2020 WR250R. The owner wired power directly into his battery for his cell phone and GPS Without a regulator. Would this drain the battery even if the bike was off? I went to buy the bike and it wouldn't start. The owner seems to think this drained it?  Hoping to buy this bike as soon as I can get it started. It's a 2020.

If we're talking about a simple USB connector, then no, it won't draw any current when not in use. If the battery is drained, he should be able to recharge it in a matter of hours and have the bike operational.