Have a try with this TWRP version ..
http://freaktab.com/forum/tv-player-...ta-android-l-m
TWRP_3.0.2.0-Geekbox-BETA_Lollipop_v160425.img
TWRP_3.0.2.0-Geekbox-BETA_Marshmallow_v160425.img
Should work on your rk3368 device as well .. Use the custom recovery.img file above and the Android Tool Release v2.35 from the first page.
If you have unified storage (no internal_sd anymore) use the marshmallow version.
Cheers
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