I discovered today that what appeared to be a boot problem was actually that my Raspberry Pi (3 Model B) and my LG monitor could not see each other through the HDMI switch. Once I connected the R Pi directly to the monitor, everything was fine (I guess it had been booting satisfactorily but I didn't realize it). This monitor is shared with my desktop computer (which has no problem with the HDMI switch). Does anyone know of a 2-port HDMI switch that is compatible with the Raspberry Pi? It's obviously a pain having to unplug and plug all the time.