Hi @Suhaimi_Napis_FBSB sorry to hear about this problem. There was a known issue in 3.8.0 and 3.8.1 that affects the reliability of booting in dual boot systems. This bug is fixed in the 3.8.2-beta1 release (see Beta Release | Endless OS 3.8.2~beta1). So, if you can get the system booted after restarting a couple of times, following the instructions at Getting Started | Beta Testing Program to switch to the beta channel and then install the update, it should fix the reliability problem. Let us know how it goes!