Won't Post, only flashing keyboard

Dell Inspiron 7306 2 in 1 (Black edition) Core i7, 32gb Intel Optane/ 512gb SSD, 16gb ram

Getting a constant flashing backlit keyboard with no boot. I've tried resetting (holding power for 60 seconds with power and battery unplugged), also tried disconnecting CMOS and battery and flea draining as well. Just a blinking keyboard once power is pressed. No special diagnostic led battery indicators either. No amber light blinks at all, just solid white battery led. Keyboard just keeps blinking. Only way to get it to stop is to unplug the battery. Once I plug it back in, flea drain and press power, with or without the battery connected, same result. No way to get to Bios(F2) or to a one time boot screen(F12). Tried booting with SSD disconnected, same result. Tried swapping out SSD with a new one, same result. The only thing that gets it to respond differently is holding the D key down to get the LCD display diagnostic, in which I do get the color cycling test and the fan will even turn on but once it's done color cycling a few times the fan shuts off and it's back to the blinking keyboard. Holding down the M key does nothing different diagnostic wise. Ram is soldered in, so no need to reseat. Downloaded the service manual, didn't find anything else useful to try.