I have a Dell Latitude 5591. It has a strange problem:
First, when the WLAN card is plug in, it will not power on when press power button, even all voltage is up (19v, 3v, 5v, 3valw, 5valw)
When I remove the WLAN card, it will start nomarlly. Then I power off and re-insert the WLAN card, it still work normally.
But, if I left it for 3 or 4 days without the battery and adapter plugged in, it will not power on, and I have to repeat the above sequence.
Sometime, when it not power on, I just unplugged the battery and adapter, wait...