Help diagnose LCD picture problem - Vestel 17MB82-2

[shakalnokturn]

TV repaired a few weeks ago for a dead backlight LED. After some hours of use the backlight is still good it now has lost the picture.

Model:
Brandt B3220HDLED (Vestel 17MB82-2 based. Mediatek MT5820LUNU)

Panel:
VEL_LCM VES315WNDS01_IPS11_32185_MB95

T-Con:
LSC320AP01-L03 (SM4108 based.)


I'm looking for a little guidance to decide where the trouble is coming from.
The symptoms came suddenly one day at power-up from standby, before there were no picture defects.

I'm suspecting the panel electronics which are unfortunately bonded to the panel itself, single COF is bonded to glass obviously but also to T-Con board.

Things I've done so far:
Disconnected and reconnected LVDS at both ends.
Applied light pressure and torsion while powered to LVDS connectors and T-Con.

Scoped the LVDS lines, there is activity and changes in stream if I bring up the TV's menu.
I didn't see anything move on LVDS cable's "SCL_I" and "SDA_I" lines these lead to IC1 (SM4108) through a few resistors.

Are these lines actually used for communication between MT5820 and SM4108?


Measured DC values of test points that had names looking power related on T-Con. (Yes, the fuse is OK...)

VIN:          +11.8V (Input from LVDS cable)
VDD1:       +3.26V
VDD1L:     +3.26V
F_VCOMR: +6.68V
VCOM:      +6.68V
F_VCOM:   +6.7V
VCST:       +6.1V
HAVDD:    +8V
VONE:      +28.3V
AVDD:      +16V
VCC:        +3.27V
VOFFE:     -9V
VSS:         -7.44V

I know I'm going to spend more time on this than the TV's worth but the learning experience is quite valuable to me.

[shakalnokturn]

I've made more measurements but still don't know what to make of all this...

DC values at test points:
CV0:        +6.63V
VREFL_L:  +0.228V
VREFL_H: +7.057V
VREFU_L: +8.26V
VREFU_H: +15.097V

Confirmed that LVDS interface looks good except for non differential lines SCL_I, SDA_I that never change state. Should they?


Also scoped some test points close to the T-Con to COF bonding, I didn't see much happen on points CK1_1, CK1_2, CK2_1, CK2_2.
Either there's no movement there or the frequency is much too high to show on my scope (500MHz probes and FE bandwidth), problem is I don't know what to expect there in normal conditions...

Anyone have any clues or suggestions on what to measure next?
A datasheet or any schematic containing the SM4108 could be helpful also.

[shakalnokturn]

More test points...