SamyGO

Unless you find someone to confirm another FW to work also on your device, I wouldn't recommend taking that risk.

Assuming you have a non CI+ device, you could:
1) get access to your TV via the serial console
-> http://wiki.samygo.tv/index.php?title=E ... 2B_Devices
2) dump the content of your mtd_exe Image ( below WIKI article should give some guidance on the how ... )
-> http://wiki.samygo.tv/index.php?title=M ... and_CRC32)
3) enable your telnet ( see section "Hacking the Firmware" in below WIKI article )
-> http://wiki.samygo.tv/index.php?title=H ... ung_TV%27s
4) write back the modified image into your flash ( see also article as in 2) )

Do everything at your own risk though ... and do it only, if you understand what you are doing.

Hope this helps.

Regards
dynamic

Good to hear that it worked for you

Regarding to the keycode to enter Service Menu, this differs based on the model you have.

Regards
dynamic