It is not perfect. I have Bluetooth working with the stock firmware. I can now use my BT keyboard to type.
I initially tried modifying the board-rk3188-box.c but it didn't work. The solution is actually not that hard, I know that the kernel built by d33 has working Wi-Fi and BT. And he uses github for the source. I go through the changes he made and decided it is likely that the BT is broken while he added BT support for the other Wireless modules.
So I just start off from the origin of his master branch and patch in the changes I made. In no time, I have a firmware with working Wi-Fi, Bluetooth and Touchscreen!
However, this only means that I am half way there. The stock firmware has several limitations. Namely, lack of 1080p and lack of rotation. Not to mention I have to root it again. The lack of rotation support is really ruining the Giant Tablet experience. I now need to figure out a way to get my kernel working with the smic firmware.
I suspect that the BT drivers are different. So first thing I did is make a backup of the /system directory of the stock firmware. And then, I flash the smic firmware over and compare with files under its own /system. I see 3 bluetooth related files with different file size:
/system/vendor/lib/libbt-vendor.so
/system/lib/hw/bluetooth.default.so
/system/lib/libbt-hci.so
Unfortunately, even after I replaced them, BT still won't work. I need to think of some other approaches.
In the mean time, my replacement monitor arrived (Thanks Newegg!). I don't want to RMA it again, so hopefully this monitor does not have wiring problem like last one.
(While waiting for my monitor, I searched for some other touch options, it seems one can buy a 32"-40" IR based touchscreen overlay for as little as $200-$300. I am quite confident that they can all be made compatible with the TV sticks. Imagine the possibilities!)