ThinkPad won't boot, how cooked is it?

My ThinkPad P50 doesn't boot or post.

If I press and hold the power button, all of the LEDs on the keyboard flash for a moment as the power and FnLk lights turn on for perhaps a second before turning back off. The display backlight doesn't light up. Unplugging the CMOS battery doesn't appear to have done anything.

Anyone have any ideas or is it just eWaste now?