most probable cause is the mDP cable different cable / adapter should solve the problem

the only thing left no removed - try removing RAM modules one at a time ( try each sodimm individually in either slot - do not forget to power unit off ( fans not spinning) as you meddle inside the ...

I think I had one such MacBook Air. It was permanently resolved by replacing the LCD assembly at AASP as the warranty was active - it did essentially qualify for DOA (wtf? - still do not know the ...

duplicate the note as many times needed. erase photos in the duplicate notes so that there are 5 or less of them pic 1 to 5 in the first note, pic 6 to 11 in the second - and so on ... airdrop them ...

do a "safe boot" once in a while if bothered by the evergrowing caches... the word ( apple kb article link - https://support.apple.com/en-us/HT201262 ) is that it cleans caches out.