Don't panic yet! A black screen on MacBook Pro can often be resolved, whether you have an old MacBook or a recent M3 device. We've been there many times (after all, we've been testing and reviewing ...
Not a devastating problem compared to what's going on, but my son has the USB-C cable that connected my little Asus ZenScreen (MB169C) monitor to my 15" MacBook Pro (2017) - and he's in lockdown ...