My PS4 is randomly turning off, and I have tried everything

Ok, here we go. So I’ve had my PS4 for about two years now, and it’s only started giving me grief recently. Essentially, I can be doing anything, from playing a game to downloading a game, when without any warning whatsoever, the console will turn off. I can immediately turn it on again, with no boot up issues whatsoever (aside from a couple beeps and a message telling me not to suddenly turn the console off). This is where things go weird, because I can play for an hour or two, have the console suddenly turn off, and turn it on again to play for six to seven hours with no troubles whatsoever. I have popped the sucker open and thoroughly cleaned it out with compressed air, I’ve put it in a nice open space with at least a foot of clearance on each side (which, for someone living in a broom closed apartment, was no small feat), I’ve played it with my tiny window open, etc. None of these have worked, and so I figured it might be something with the software. So I backed up my saves to an external hard drive, initialized the system, and then restored it. I was able to play with exactly zero problems for a day, until today, when it turned off again. I tell you, I let out a cry of despair that would win me an Oscar if I was acting. But I wasn’t. And now I have no idea what to do. Do I buy an external fan? If my room is poorly ventilated as a whole, which it kinda is, will an external fan help, or am I just perma-boned? If it’s a software issue, should I not have restored the system with the backed up game files? Do I just throw it at a repair shop and pray they don’t rip me off? Do I just toss the evil thing out the window and blow another $400 on a console that will probably break on me again in about a year? Please help.