Thanks a million! That did the trick!
After many tries i decided to try from the ssh terminal.
simply did the followings;
ssh root@myappletv
Apple-TV:~ root# /usr/bin/mHelper install com.firecore.media
Hit http://apt.thebigboss.org stable Release.gpg
Hit http://dl.firecore.com Release.gpg
Hit http://nitosoft.com Release.gpg
Ign http://mirrors.xbmc.org ./ Release.gpg
Hit http://cydia.zodttd.com stable Release.gpg
Hit http://apt.modmyi.com stable Release.gpg
Hit http://dl.firecore.com Release
Hit http://apt.saurik.com ios/690.10 Release.gpg
Hit http://apt.thebigboss.org stable Release
Hit http://nitosoft.com Release
Hit http://apt.awkwardtv.org stable Release.gpg
Ign http://mirrors.xbmc.org ./ Release
Hit http://apt.saurik.com ios/690.10 Release
Ign http://dl.firecore.com Packages/DiffIndex
Hit http://apt.awkwardtv.org stable Release
Get:1 http://apt.modmyi.com stable Release [1341B]
Hit http://dl.firecore.com Packages
Ign http://nitosoft.com Packages/DiffIndex
Ign http://apt.saurik.com ios/690.10/main Packages/DiffIndex
Ign http://mirrors.xbmc.org ./ Packages/DiffIndex
Hit http://apt.saurik.com ios/690.10/main Packages
Hit http://apt.awkwardtv.org stable/main Packages/DiffIndex
Hit http://nitosoft.com Packages
Hit http://mirrors.xbmc.org ./ Packages
Hit http://apt.modmyi.com stable/main Packages/DiffIndex
Get:2 http://apt.thebigboss.org stable/main Packages [925kB]
Hit http://cydia.zodttd.com stable Release
Hit http://cydia.zodttd.com stable/main Packages/DiffIndex
Fetched 926kB in 35s (26.4kB/s)
Reading package lists… Done
2012-05-25 17:30:07.549 mHelper[339:707] installPackage: com.firecore.media finished with status: 0
2012-05-25 17:30:09.212 mHelper[339:707] termStatus: 0
Apple-TV:~ root# reboot
It took few tries as it blocked few times toward the end but after few trials it worked.
me too… same problem here…
Same here, no media player install possible…very frustating 
The problem is one of the repo’s the installer uses is shared with iOS devices and is being hammered from everyone trying to upgrade. You can use the steps in the post below to fix it now, or wait a few days and re-install.
Tried to instal several times and suddenly it works 
To those of you that have had success with the new unthethered update and have been able to install MediaPlayer, where does the maintenance menu appear? I got the FC logo, installed latest atv flash black, restarted but all I get is the normal Apple settings menu. I have disconnected the power and plugged back in, have ssh’d in and gotten kicked off the server 3 times before I was allowed on and downloaded as per jonez instructions:
and on the fourth attempt it said 100 percent and done. Did all of the above again with no success. Frustrating but it is fun trying to figure this all out.
… i had same problem rofik@o2.co.uk
… i had same problem rofik@o2.co.uk
… i have tried so many times still no luck rofik@o2.co.uk
… i have tried so many times still no luck rofik@o2.co.uk
… dude i am having same problem , jailbroken with latest season pass atv2 5.2 and atvblack 2.2 .. now bloody media player installation failed .. any plz help { rofik@o2.co.uk}
… done all this step dude still no luck any other idea plz help… rofik@o2.co.uk
… done all this step dude still no luck any other idea plz help… rofik@o2.co.uk
… done all this step still no luck plz help … rofik@o2.co.uk
… done all this step still no luck plz help … rofik@o2.co.uk
…done all this still no luck plz help … rofik@o2.co.uk
…done all this still no luck plz help … rofik@o2.co.uk
…I’ve unplug reboot etc many times still cannot install media player & i have paid ?? i hope they pay my money back???
It’s been over week still not fixed …still media player installation failed ’ I’ve
Sent video & diagnostic to firecore , but problem still remain i ask for refund
My money back. rofik@o2.co.uk