SamyGO

Yes, lot's of people made this mistake. But they reverted their TV's.

Problem you faced is "authld". Shortly Samsung's program in TV checks firmware for if it's changed. On your situation, it founds the change and shuts down the TV.

Fortunately some members made great success about beating authld. It's still alive and beating us too. But I think you can disable it for temporarily (for gain enough time to reinstall your 1008 from TV menu, that fix the issue.)

Experts will help you soon. I don't wanna talks on subject that I don't know exactly. There are professionals here

sg75 wrote: After that I use the Software Upgrade Menu to switch back to 1008.

Do you have the option to switch back to 1009 using the "software upgrade menu" ?

Otherwise try "touch /mtd_rwarea/PartitionSwitch_0_0" and after the file is been created then remove the other switch "rm /mtd_rwarea/PartitionSwitch_1_0".

sg75 wrote: But only for a minute then it switched off without my fingers on the remote.

In fact, that's our friend "authuld" which is not happy that you modified bml10 and bml11, but kept the hashes in bml3. The hashes match with 1008 partitions, but not with 1009...

sg75 wrote: So my question is, what can I do to revert it back to 2009.1 so that I can use the TV again?
My own humble efforts involved a 'killall -9 authuld' within the few seconds left after running the trojan app.
But that buys my only approx. an additional minute.

The process is as follows:
(1) linux kernel checks integrity of authuld itself. If check fails -> kernel panic
(2) authuld is started as kernel thread.
(3) the kernel waits for some time for authuld to return "OK". If authuld does respond. -> kernel panic
(4) authuld shuts down the system in case of integrity/hash failure.

According to (3) you kannot "killall -9 authuld" since the kernel would not get a message and thus result in kernel panic.

sg75 wrote: I see. Let me guess, the kernel can't be patched cause it is in a read only memory?
Still, "killall -9 authuld" extends the time from one minute to about 2-3 minutes until the system shuts down.

No, the kernel will not be loaded if signature check fails. Kernel signature is checked from bootloader, which in fact is not writeable.
OK, you are right, killing authuld gives some more minutes.