820-00165-A with no signs of damage. Supposedly suddenly died during an SSD upgrade and subsequent software reinstallation at another shop. When the display is plugged in, the device rapidly boot loops with a chime every 2-3 seconds during which the internal display is blank with backlight, SMC bypass, reset, etc. has no effect on this behavior. When the screen is unplugged (Testing bare board, no SSD, only speaker connected) the device only chimes once and then seems to hang forever, no question mark folder on external display (but it does recognize that an input is connected when the device starts), no caps lock, boot current seems normal until it settles in at 500-600mA and remains there. A quick check of all coils shows no major shorts, I'm starting to wonder about an SMC issue? Am I correct in thinking that the flashing question mark should show on an external display with no SSD installed, or is this limited to the internal display?