Yogenthiran Ponnambalam 4 Powered up board with pi OS from SD card created by downloaded imager. Came up fine. Ran some python code which worked fine. Left board powered for 24 hrs. Type "sudo reboot now" from terminal. Boot process fails with green light constantly on. Same SD card boots my 4GB Raspberry pi4 perfectly. Can't return product 'coz I threw away the box not expecting this to happen.Ordered replacement that arrived late. Amazon did give me a 300 yen credit for future purchase. Replacement works as expected. Found others reporting same issue on Raspberry pi forum.