A blinking red light indicates that the battery has a low state of charge and it will not start the laptop.
Hey I have an Alienware m15 R4 that when the power supply is jacked in, the power light blinks red continuously. Some history: when this issue first occurred I was using the computer and it shut off with the light flashing red then stopping and the light on the power cable turning off as well. The connection of the cord to brick has always been loose so I replaced the power supply, thinking it faulty. With the new power supply when I plugged it in, the power button still flashes red but it doesn’t stop until I unplug it. What could be the issue here and how would I fix it? I’m thinking if the issue was the power supply then the laptop should turn on when the power supply is connected, no? 
m15 R4, power light continually blinks red