Rispondi a: After reassembling my laptop it just black screensI have a K55N also, I installed the Hard drive in a caddy and an SSD, and upgraded the ram , all just a few days after buying it, and the same happened after. After a while, I realized that it will take up to 5 minutes to start. with no further problem. I have the bios version 217, and Asus claims that the problem should be "already solved" but it's not. Is yours the same problem? Have you just "waited" ?