Ubuntu freezes on boot or won't boot

I have boought 4 asus mini Pcs and installed ubuntu 18.04 and some required packages and libraries I needed. My problem is, One of them freezes on boot, it was ok at first but after some restarting, it became faulty, I thought maybe the problem arises from hardware, but I installed windows 10 on it and it booted successfully. How can I find the problem. If it's a hardware issue, how can I make sure? The mini pc is ASUS pn40 with 120gb ssd and 4gb ram.