Avoiding rpi-udate?

Hi all,

I was trying to make the rpi3 integrated wifi work…
well I couldn’t manage until I upgraded my kernel with the latest rpi-update…
then suddenly ifconfig would show me wlan0 and I was able to ssh through wifi…
But zynthian doesn’t seem to work on my Z-box anymore … blackscreen

systemctl stop zynthian
killall -9 jackd
speaker-test

gives me sound so that’s working

and the only thing I did from my currently working image was:
rpi-update
sudo reboot

Apparently they changed sth which make zynthian go black

uname -a
Linux zynthian 4.9.11-v7+ #971 SMP Mon Feb 20 20:44:55 GMT 2017 armv7l GNU/Linux

this is the log of my rpi-update
*** Raspberry Pi firmware updater by Hexxeh, enhanced by AndrewS and Dom
*** Performing self-update
*** Relaunching after update
*** Raspberry Pi firmware updater by Hexxeh, enhanced by AndrewS and Dom
#############################################################
WARNING: This update bumps to rpi-4.9.y linux tree
Be aware there could be compatibility issues with some drivers
Discussion here:
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=167934
##############################################################
Would you like to proceed? (y/N)
*** Downloading specific firmware revision (this will take a few minutes)
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 168 0 168 0 0 304 0 --:–:-- --:–:-- --:–:-- 304
100 53.4M 100 53.4M 0 0 1673k 0 0:00:32 0:00:32 --:–:-- 1592k
*** Updating firmware
*** Updating kernel modules
*** depmod 4.9.11-v7+
*** depmod 4.9.11+
*** Updating VideoCore libraries
*** Using HardFP libraries
*** Updating SDK
*** Running ldconfig
*** Storing current firmware revision
*** Deleting downloaded files
*** Syncing changes to disk
*** If no errors appeared, your firmware was successfully updated to 3e1c3e9ba2 b948e6023114b9633223363da78679
*** A reboot is needed to activate the new firmware