Need advice about buying a rebooting Key2

Someone is selling a used Key2 online which freezes and reboots randomly. Apparently this is a common problem with Key2 phones but I was wondering if it is more likely to be a software rather than hardware problem?

The end goal is to put LineageOS on it so if it's software I don't mind. It's much more cheaper than other used Key2 devices and I wonder if it is worth the risk.