So you've got a RK3288 in masked ROM mode. That is the lowest form of life, when everything is broken. Can your Rockchip utilities tell you anything, whether you still have partitions?
There is a long thread in XDA developers here that might be worth a read.
https://forum.xda-developers.com/t/t...vices.2915363/
Edit: I presume that you've tried a long reset push a few times to see that it always comes back to the same thing?