I had this exact same problem. After having to replace the screen on my 2020 MacBook Pro 13" having thrown coffee over it, it wouldn't power on. However, I researched and found this article.
It turned out that ribbon cable had broken, presumably internally, and when I flipped the compression latch up on the larger of the two ends, it somehow let go and launched itself into orbit never to be seen again!
I ordered a new cable from Germany along with some Kapton tape. I shimmed the end of the ribbon cable with two pieces of Kapton tape and using tweezers, persuaded the cable into the connector (okay, I admit the wrong way up first time, second time lucky!) At this point I turned the laptop over and powered on.....nothing. I did wonder if the battery had run flat, unlikely but not impossible, so I connected the power cable and of course it powered up. The difference this time was a battery icon on the display whereas before there was no icon and the display was multicoloured flashes and full speed fans etc. The battery was now showing 100% so I guess it needed a 'jump start' using mains power.
It's now happily reloading Monterey and I'm hoping all is resolved.
Thank you for the above, it inspired me to have another go at repairing the old girl, though what I will do with it I'm not sure as I replaced it with a new 14" MacBook Pro. Maybe some lucky soul on eBay.......