External screen not recognized anymore

Hello,

My MBP 15” Mid 2010 with NVIDIA GT330M doesn’t recognize anymore my U2713hm screen plugged by displayport. (clamshell mode)

If I connect it with a displayport cable it either doesn’t recognize it and in the console it reports: WindowServer (Core Display)

[ERROR] - Unknown CGXDisplayDevice: 0x41dc9d00

Or now when it works randomly it’s detected as a generic screen and only outputs 1080p instead of the 2560px resolution.

Connected with displayport to DVI it doesn’t work too, it only works in hdmi limited to 1080p (screen’s HDMI limit)

I tried the following:

new cables, 2 different displayport cables

DDC/CI mode disabled on the screen

Factory reset of the screen

a couple of PRAM and SMC reset

10.13.6 clean install

removal of com.apple.windowserver.plist

Nothing works.

When this started I replaced the capacitor that is known to fail on this Mac but it didn’t change anything.

The motherboard was replaced by Apple, it looks like it was a refurbished one and the capacitor I replaced looked like it was already replaced as there was green paint dots added on it, the new one is the one advised on forums.

Also the computer had the thermal paste replaced.

There is no kernel panics, no visible problems, only the external screen not recognized.

Is there anything I could do to fix this?

Thank you.