My thoughts have changed many times. It was such a dark night. I don't think Brandon could have made it 3 miles in the time allowed considering the circumstances. Moonlight was almost zero. I don't think the conditions were right for him to text due to his condition, injury, etc. Although the texts allegedly came from his phone, I am suspicious whether he sent them or not.
I think it's very possible he went into hiding with help, but it wasn't pre-planned or at least pre-planned very well. It's possible the last phone ping came while he was being driven somewhere by someone and perhaps finally thought about shutting off the phone. Standby times of digital phones are quite long and I think it unlikely that the battery just went dead. Even if he had a smart phone with a flashlight app the power consumption by the LED isn't so much as to drain a battery in minutes. If he went into hiding it was with help, even if his "helpers" didn't know of the plan until that night. As for the 401K he may have thought he didn't have time to wait for it to arrive.
On the other hand the facts are starting to add up to completely irrational behavior. Taking off late at night, not noticing the low gas until he runs out, abandoning his vehicle, hiding out from help even though injured, and the puzzling 911 call. Unfortunately this scenario would almost certainly mean he is deceased.
The third possibility, less likely, is that he was attacked after he ran out off gas by a person or persons for some reason. Someone may have taken advantage of the situation and he ran for safety. But doesn't make as much sense as he doesn't come forward when his brother and LE arrive.
And fourth: perhaps he was abducted by aliens and he shut off his cell phone to avoid roaming charges.