After connecting the FTDI cable, it was possible to watch the debug output.

You can interrupt the normal foreground code execution with CTRL+C, and voila: there is a Linux shell!
I immediately tried to dump all of the decrypted data to the external USB drive.
Frequently, the watchdog is hitting and the CPU is reset, so this is a hideous task.

A short summary of the boot process:

1. low level boot loader (I don't know if it is uboot)
2. Kernel booting: 2.6.35, with following parameters: 

   root=/dev/mtdblock2 rootwait lpj=1814528 console=ttyMT0,115200n1 quiet mtdparts=mt53xx-nor:192k(loader),1216k(kernel),8M(root),64k(ro),1664k(rw),960k(ro2) _2nd_4M

3. Call /basic/autorun.sh to start the device software. Normally, it simply mounts the USB drive & calls /basic/post_init.sh & /basic/vestel.bin. If MB82_DEVELOPER or MB82_AUTOTEST is set (whereever these are set usually), some stuff from the USB drive is loaded.

4. post_init.sh calls load_usb_modules.sh (which loads all kernel modules) & a binary ./dtv_svc (no idea what this is doing).

5. vestel.bin is the main TV service program

With my TV, there was cleary something wrong. I received repeating error messages:

[Montage RS6000 _mt_fe_tn_set_reg] RS6000 set repeater error! 

Now what???
First of all: what is this RS6000 my TV is complaining about?

When searching the error message in the vestel.bin file, there are also different messages related to the tuner so I think this is related to the tuner IC:

#strings -n 20 vestel.bin | grep 6000 

My version of the technical manual does not list this chip (I have to acknowledge: Vestel provides the full schematic, this is really fine!!!), so it seems I have a different board.

Nevertheless, I need to open the shielded tuners. Here we are, a M88RS6000 IC.  This is the DVB-S tuner.

I didn't find any datasheet, by there is Linux support (but with firmware blobs).

Maybe there are some infos if we need to do something about it...