Seems like the common case of dead battery syndrome. When you get to your desktop, go to the apple logo in the top left, about this mac, system report find power on the left side and take a screenshot of what it says and post it here. If it says that condition is not normal, says theres no battery or if the cycle count is over around 600 your battery is shot and you need a new one. Do all of this ofcourse with the battery plugged in.
Hope this helps and good luck fixing!