Splashscreen working, then goes Black RPI 4 400

[senses88]

Hey there and merry christmas to everybody.

This is my first post on this forum.

Yesterday i got an update on my Recalbox RPI 4 400.

I was running Recalbox 7 just fine. After the update my TV does show the splashscreen and just goes black after this.
A few seconds later a floaty message from my TV pops up saying that it is an unsupported format.

(Sound Output is working fine, so i guess i am plugged in to the correct hdmi port)

(I am running a LG C9 OLED TV)
It does run just fine on my Samsung TV in the bedroom.

Does anybody have any ideas on how to solve this?

I already did a fresh install after thinking there was a problem while updating.

I am quite new to this topic so i am hoping for some help.

Thx to anyone reading this and helping me in advance.

Greetings Thomas

[senses88]

Hey there, i am replying to myself now

After using ssh to edit the config.txt file and enabling hdmi_Safe=1

I can get into ES. The problem now is, that the resolution and overscan is completely messed up.

How do i change the value of safe mode?

I feel, i am so close to it.

Does anybody know, what the changes between 7 and 7.1.1 are and why normal hdmi mode is not working anymore ?

greeting Thomas

[Alibaskins]

@senses88 hello Thomas,

I have exactly the same problem... Same TV...

Have you find a solution ?

[Alibaskins]

@Alibaskins
So now it's working when i uncomment this :
hdmi_force_hotplug=1