If everything works then your FL 2.0 is good (Assuming it passes a visual test, don't waste your time trying to replace). Having a blown fusible link won't drain the battery. If anything it will prevent your battery from being drained. I'd start by recharging your battery, then check to see if there's a draw. I'm sure you're beyond this, but it's a common mistake for van newbies to not turn the ignition off all the way. Since the ignition tumblers are weak, the key can usually be removed even when its still in the accessory position.
It's also possible the alternator may have a shorted diode. Here's a thread that may aid you in identifying and repairing a draw. Tim
https://www.toyotavantech.com/forum/...r+draw+circuit