Check if power supply is enough for your pi and USB devices. 2.5 Ampere is recommended. If you got nothing on USB, then 1 Amp should work.
Sometimes a USB device tries to draw more than 0.5A , for instance a 4G network modem, in that case you need to supply power to that usb peripheral using a separate adapter. Connect the RED wire from adapter to usb device’s RED wire, keep GREEN and WHITE connected to rasppi. All BLACK wires should be combined. Keep RED wire coming out of rasppi usb cable, unconnected.
OH has logs in /var/log/openhab2/ : audit, event and main log.
If you want Linux logs, journalctl and dmesg are the tools, by default they report current boot logs. You can search on internet how to to show previous boot logs, since you are investigating a crash.