When you have a new question, it is best to select "New Thread" at the top left and start your on discussion...
Anyway this would depend on the *specific* power steering system you have and the *specific* power brake system you have.
If they are both electronic, then it is possible your vehicle had a low charge on the battery. Some electronic systems will not function right if there is not enough electricity to power them.
And if they are both electronic, then I think the only things in common would be a vehicle speed signal, and a computer local area network.
I don't know if the abscense of the vehicle speed sensor signal would cause these things to not work? Note that this signal is also used for the speedometer. So if this happens again, check to see if the speedometer is working. Also if the vehicle speed sensor signal was missing, I would think you would get a check engine light and a diagnostic code for this.
The other thing in common is the local area computer network over which the vehicle speed sensor signal is communicated to the various electronic modules. However again, if this was not working, you would get a check engine light and a diagnostic code.
Therefore I would guess a low voltage on the battery for now. These newer vehicles have a constant drain on the battery due to so many electrical things in them. So leaving it sit for 4 weeks probably drained the battery.
There are solar battery "maintainers" available like at the following link. This keeps the battery charged. And this is good if you have your vehicle parked for an extended period like at an airport. (Park in the sun.)
http://www.siliconsolar.com/12v-solar-battery-maintainer-2_4w-p-16677.html