Fridge/Freezer Not Cooling Down Samsung RS20CCMSn plz help.

I opened up the panel at the rear/back. it was HOT. carefully removed most of the dust. when i switched the electrics on the fan was working and the compressor was vibrating so i am assuming that was working too.
i couldn't see any frost anywhere.

the freezer wont go below -9 (15) and the fridge is staying on 4 (39).

what could be the problem?

same as rs21 you find all on this site if you search for it