Answer to: Doesn't turn on and says to download custom OS.Our phones aren't exactly similar so. What works for the other might not work for you. I have a Samsung Galaxy Tab 2 10.1. Note that what I have is a TABLET, not a phone. According to the Samsung's site Help category, in order to go to the selection of Resetting (i.e., Wipe cache partition, factory reset, reboot system) I must hold the POWER BUTTON & VOL. UP together. However, holding them 'caused my device to head onto "Custom Os installation". I figured out, what if I try holding the vol. down instead of vol. up? Now, that was when it went to the selection of Resetting. So, in simpler words: Try changing it up. What worked for me: Hold POWER BUTTON + VOL. UP = CUSTOM OS INSTALLATION Hold POWER BUTTON + VOL. DOWN = ANDROID FACTORY RESET SELECTION Remind you, this is what worked for my Samsung Tab 2 10.1.