So, long story short, there was some kind of a loose screw that came off inside my Acer Nitro 5 an515-53 (bought it just a few weeks ago), very basic common stuff, so I thought I'll just disassemble it and re-screw it.
However, before I got to the loose screw, right after I opened the cover, the HDD cable (Not the one that you insert into the HDD itself, but the small one (I'll include the pics)) came off from its slot. It happened because the HDD itself was still screwed onto the cover (wasn't even planning to take it off), and I was applying some force to the cover since it was quite sturdily attached. This, of course, causes the cable to be unplugged.
Now when I try to turn it on it says "no bootable device", so the HDD isn't registering anymore.
Am I screwed? I couldn't find any threads online with others having same issue, and there's no visible slot that the cable could be going in. Here are some pics: