My Nexus 5 goes into very early bootloop - basically during the initial 2-5 seconds from turning on it goes into bootloop. It also restarts even when in recovery mode (dont even have time to make any selection before it restarts). My suspicion is that this is a HW problem - just wanted to confirm if the phone is dead for good before I throw it away. If it is HW, it would probably require main board replacement, which would be very costly I assume? Or could it be something different?
Going to include my resolution in case it helps someone. The problem turned out to be malfunctioning power button, which the phone was taking as pressed all/most of the time. Some random jamming, pressing and squeezing of the button fixed problem. From what I understand this is relatively common problem on Nexus 5,as many are getting their power button replaced.