My lenovo b50- 30 started powering off on its own 2 days ago. I thought it was over heating , but I'm not convinced since it's doing it after being off for hours . Its random. Maybe 2 minutes after booting up or an hour. When it happens it won't immediately turn back on either. I tried without my battery. Still did it. Did I fry it?
If it was fried, it wouldn't turn on. It does sound like overheating is the issue. I would monitor the temps and do the following soon as if it goes to long then you could fry it.
If it is under warranty still, then contact the manufacturer about fixing it. However if it is out of warranty, then you or someone you take it to can open it up and clean out the dust and debris. Should that not do it, then replacing the thermal paste would be next. And if that doesn't help, I would try replacing the fans.