I pulled lower cover off to see if there was any flame. When I did this the furnace stopped and it has not re-started.

Only post once, duplicates take up space, get merged and confuse folks. Many furnaces have a safety interlock switch on the door. The unit will not operate with the door open but normally there is a small poirt or lense for you to see the flame.Reinstall the door, set stat for heat higher than the room temp. Look thorough the lense or feel the exhaust stack to confirm flame