Why external monitor is blinking on and off,power button won’t turn off.

Sunday morning I turn on my computer and I see its blinking on and off. Normally it blinks on and off to like boot up or something. I connect my dell laptop to my external monitor. I use a cable with hdmi and the display part on the other side. I plug them in and it shows on the monitor screen.
I sat waiting for it to load but its taking longer than usual.I plugged out the power cord and pull the monitor. I remove four little plugs from the side of the monitor, then when plugging in the power cable cord,it shocks me on my fingernail. I had a thought the power cable needs to be changed. Is that it?. Yea so I used my sisters laptop yesterday while having the monitor plugged in and eating for a longtime hoping for it to boot up or turn on but nothing. The morning when I saw it taking long to boot I connected my laptop to my television to see and its working. It display on the television. Do you think its the power cable Cord also?. Ill be buying one today to see if it will workIm hoping it does because my laptop screen is broke and ink is running out. Help me please?