I FIXED IT!!!!
I had the same problem... and its insane we cant update the firmware ourselves... this machine should have a factory reset button you access with a paper clip like all other machines BTW!
SO, I tried like 30 or 40 reboots, sometimes using the power plug, sometimes unplugging the material station... and non of that worked... sometimes it hung on an all white display, sometimes it hung at the ultimaker logo screeen... I never got to the menu..
But the long term charge on the capacitors got me thinking... I unplugged the machine overnight! In the morning it booted up! first time I'd gotten my machine back in weeks!!!