It could be both software and hardware related-problem. Or it could be either of the two.
If I were in your situation, I would try to troubleshoot it first as hardware-related.
I would turn off the power, remove the power plug and battery, open the laptop
and re-seat the HDD cables, memory modules, and wi-fi card. I would also check for dirt/soot
and do some cleaning if it needs be.
If the problem still persists, I would do a clean install of the Windows OS.
Considering the laptop you have newly acquired is a used one, the OS might
have been corrupted, thus, the inability to function properly. So, it would be a
better option to have a fresh set of Windows OS installed. I assume you still
have the Windows OS Product Key sticker at the bottom of your laptop?
Whatever the Windows version is, you may download a copy of it and activate
it with the product key.
But if you try installing a fresh batch of Windows OS and it still wouldn't load,
you'll know for sure it's a hardware issue. In that case, it could be any thing
like a failed HDD or RAM. Worse, if its the motherboard, GPU, or the CPU..
ASUS G74SX-3DE