[How-To] Rollback on old FW...

Here is information about customize your B series firmware..:!:This forum is NOT FOR USER questions or problems but DEVELOPER.

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Re: Rollback on old FW...

Post by manga00 »

edelfalke wrote:Easier (and faster) way is to change partitions back by /mtd_rwarea/PartitionSwitch_X_X.

a little bit accurate

rm /mtd_rwarea/PartitionSwitch_1_0
touch /mtd_rwarea/PartitionSwitch_0_0 or

rm /mtd_rwarea/PartitionSwitch_0_0
touch /mtd_rwarea/PartitionSwitch_1_0
LEXXB750 T-CHLCIPDEUC 2006 pached with Samygo Extensions
channelinfo, AVRFIX 2, SamyGo PVR+,Lan Remote with autostart over gdbtrick

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Re: Rollback on old FW...

Post by cyberdemon79 »

Hi there,

@clara: It seems that your mtd_exe partition was on bml10 and you overwrote it with the contents from bml8
(on an b650 bml8 is the primary mtd_exe partition and bml10 is the backup partition, it seems that it could
be the other way round on your device). If you have never done a firmware-update before, your mtd_exe backup
is blank, which means that your real mtd_exe partition got erased.
It is kind of a semi brick for which we (as far as I know) haven't a solution for now.
I'll try to describe the problem:
The (unmodifiable) bootloader loads the kernel from the mtd_boot partition (haven't got the bml number nearby).
The kernel starts up, mounts other partitions (one of which is mtd_exe on bml10 (or bml8)) and launches the
main (userspace) application exeDSP (that will do everything else, the kernel doesn't do, such as displaying the
tv-image, osd-men?s, etc.
So the kernel on your device runs perfectly fine, but the main program doesn't because it may be erased
(the rebooting after a minute is caused by signature checkung of the partitions which doesn't match anymore
cause the data is now modified).
The TV would work again if you could restore the contents of bml10 (can be extracted from another device
or from a firmware update).
The main problem is that nearly every way to communicate with the device is done through the main exeDSP application.
You would need a way to run software (enable telnet or something like that) to manually restore the partition.
The only way that could work (cause the code for that is in the kernel) would be exLink, which in turn requires
that you enable the debugmode on the exLink port in the debug menu (which in turn resides within exeDSP I assume).
You may be in luck and have a still working exeDSP (I doubt it but you never know...), try to enter the service-menu
combination (see the wiki) and if it comes up, enable exLink debugging.
If this works, one could try to bring the tv to execute the emergency.sh file from an attached usb storage,
but the requirement for that would be a working debug menu.
For now, we don't know of another way to restore your device (aside from a physical flash desolder/reflash/resolder)
than to call samsung support.


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Re: Rollback on old FW...

Post by erdem_ua »

stejo79 wrote:Being clueless on linux and telnet commands, I been trying to understand and follow the instructions on the wiki to downgrade my 3000 firmware on a 40b650.

I found out that the tv is using tbml10, so tbml8 should be the backup. The problem is that when I'm trying to mount them so I can check out the versions, tbml8 returns nothing, after waiting for a couple mins. And tbml10 returns failed to mount, device busy. Since I couldn't doublecheck the exact versions installed, I didn't dare proceed with the swap. Any idea why this is happening? Should also note that the TV is connected wirelessly to the lan, using the official dongle and the signal ain't that strong. Also, it's not a new set with 3000 installed only. It used to have 2000something before it got "upgraded".

Any help would be greatly appreciated.
I advice you to use ethernet cable for connection. Instead of mounting that partition at TV, please copy contents of that partition to your computer. (like mounting NFS/Samba directory by hand or copying to USB dongle)
So you can check partition on your computer. And you could look into it if it's empty or not...

klampfer wrote:Ok. I have Samsung LE52B750. I followed instructions on wiki and sucesfuly rollback from 3001.1 to 3000.2. SUPER!
Now, I want to roolback to 2006 firmware, but instructions on wiki for old firware is not very good (something to mount...). Can you please tell me step by step to roolback to older firmware, like it was written for roolback from 3001.1 to 3000.2?
I don't even thought if Telnet Enabler working with 3001.1 device. Revert backing is working via enabling alternative firmware link. Since you are already alternative firmware, you cannot revert it back to any earlier version with same technique.

You needed to update your current alternative firmware location. (3001.1 loaded) You can force to update those locations IF ONLY IF you have CI device. CI+ devices will enter bootloop!
You can look instructions for Force Revert Back wiki page (dangereous way section).
I advice you to use Boot External Firmware via USB device for experimentation. With it your are in the safe side and could recover your TV later if you bricked...

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Re: Rollback on old FW...

Post by edelfalke »

T-CHL7DEUC seems to be non CI+, therefore no problem with authuld.
Last edited by edelfalke on Mon Aug 02, 2010 1:56 pm, edited 1 time in total.

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