Lenovo T550 won't start

This morning the Lenovo T550 laptop simply doesn't start. Red charge LED not coming on with charger connected, no power button action, zip. It worked normally through last night. I normally get warnings if the AC charger becomes disconnected (it is nearly always connected). Battery is a Li-Ion "68" and appears to have 11.9V, 11.1V and common on its terminals (not sure which is which). AC charger is reading 20VdC. I have seen some sites talking about pulling the battery out, holding the power button down for 30seconds and spinning around 3 times, etc. but all for other models as far as I can tell... Thanks much