I had this problem only yesterday.
My player was dead, black screen and the hidden partition don't open
What I did was this:
1) Connected player to usb
2) Ran the RKDM tool
http://mympxplayer.org/rk27dm-repair...706-df947.html
3) Stopped the RKDM tool as soon as the player was in Rockusb mode - check in device manager.
4) Run the
UPGRADE tool (NOT RKDM tool) and loaded my firmware folders started the upgrade
5) The firmware partition was then repaired by the
UPGRADE tool.
Problem you have is you must have a working firmware backup which you don't appear to have.
For anyone else who has a broken firmware partition that doesn't open, only the
UPGRADE tool will fix it(NOT RKDM tool), but you must be in Rockusb mode to use it, the way to get into rockusb mode is to run the RKDM tool and stop it as soon as it puts the player in Rockusb mode.
The
UPGRADE tool is here:-
http://mympxplayer.org/rockchip-rk27...v25-df881.html
I also posted this already:-
http://mympxplayer.org/rk27xx-series...ide-df957.html
The right firmware I can't help with, if you didn't do a backup it's trial and error I'm afraid,
just try RK27xx firmware that looks most like your player
Good Luck!