So now all is ok?
Regarding 50/60Hz, uEnv.txt and fan control: YES! Many thanks for your support! The Matrix is going to get much more useful with your fantastic efforts on the implementation of "official" OpenELEC on this device Why ist the Matrix not mentioned under Freescale iMX6 Builds on the official OpenELEC site? Does TBS not pay them?
But there is still this big issue regarding (u)SD-Cards (see first message of this topic).
About sed: I forgot to use -i argument which means edit in place .
Not to be curious but what would be the correct command string?