Dell laptop won't wake up from sleep mode

So, here’s the situation I’m facing. I picked up this new Dell laptop from Best Buy just about a week ago, and it seemed like a solid purchase initially. However, right after it was assembled, I noticed it had this odd habit of waking itself up from sleep mode constantly. Fast forward to two days ago: I decided to manually put it into sleep mode myself, and since then, it’s been completely unresponsive. It won't wake up when I press any of the keys, hitting the Fn+F1 shortcut does nothing, plugging in a USB device fails to trigger anything, and even the usual tricks that work on my desktop PCs aren't making a dent. I’ve tried holding down the power button for what feels like an eternity, but nothing happens. Since it has an internal battery, I can't exactly pop it out to force a reset, which is a bit of a headache. Being someone who spends much more of my time tinkering with desktop rigs rather than mobile setups, I'm feeling a little out of my element here, so I would truly appreciate any insights or suggestions you might have. For context, the machine is a notebook Dell Inspiron running Windows 8.1 Pro x64, and I've already installed all the drivers from the disc that came in the box. I'm really crossing my fingers that this is just some weird software glitch that we can iron out once it finally decides to wake up.

Did you take it back to the service center where you originally bought it to have them look at it? 😕

I’m tied up at the moment and can't get to it quite yet, but I was just wondering if there's anything I should probably touch up or fix before I find a good window to drop it off for you..

To be honest, nothing clever comes to mind... 😕
I had a similar issue years ago with my Dell laptop, though I managed to fix it just by leaving it on the charger for a while until it behaved again. It still works fine today... Back then, there was clearly just a temporary glitch with the battery.
As for the folks over at Best Buy, the most you can expect from them is a polite explanation of what’s wrong with your computer.