When our S 100D was delivered, the first update failed to install. The Service Center had the car for an extended period, and after multiple attempts to install the update at the SC, they ordered a replacement processor.
But...
When I got home, I was able to get the software to install. I did a reboot of the processors, then a "Power Off" of the entire car (using the console commands), and then another reboot of the processors.
And... the software update installed. And we then cancelled the processor replacement.
And, if that doesn't work, call Tesla and ask them to push the update to your car again - and try the above reboot/power off sequence.
Since the initial update failed issue - subsequent updates have installed correctly.