"Intermittent" black screen. Touchbar and external monitor works fine

Hi everyone !

I bought a second-hand Macbook Pro 13" from 2016 that was sold as display not working. Touchbar is working and the laptop is usable properly when plugged to an external monitor.

I thought that maybe a cable wasn't correctly plugged inside so I followed iFixit tutorial to disassemble the display and check every connector to make sure everything is ok before reassembling it. It went well and I didn't find anything unusual.

After reassembly, the laptop turned on and the display seemed to work correctly. I erased the SSD to prepare it for installing a more recent macOS version and got to the point where the screen is stuck on a folder with a question mark. Turned it off to do the installation later and when I went to turn it back on, the screen was black again and I can't find a way to fix that.

I think the logic board is ok since the laptop works normally when plugged to an external monitor. Same thought for the display itself because it did work briefly.

What can I do ? Replace the full display assembly ?

Thanks for your answers !