2015 15” Retina MacBook Pro - Chimes But No Image

So basically when I power on my MacBook, it chimes but the screen is blank. I’ve done CMOS, PRAM, NVRAM etc. everything. I’ve shined a light through the logo and I can see the flashing folder (removed my SSD). I took it to Apple and they said I’d need a screen replacement for $600. But they said I could still use it with an external monitor but it doesn’t work! I’ve tried HDMI and it doesn’t work. I can swap out the screens myself but before I try, what if it isn’t the screen? Apple said my logic board was fine so I’m kinda confused here. Non liquid spills or anything like that. I don’t know if it’s the fuse, the screen, or what’s next. Help!