HP vs19e Computer turns on Monitor stays Black. blue light blinks

My computer recently had issues and was being repaired. I now have a working computer, but I have to turn the power on and off about 20-50 times before monitor will come on. The computer place says its probably that my monitor is bad??!! When I turn computer on the monitor stays black but the blue power light on monitor blinks steadily. I have to keep turning computer off and on and it will eventually come on. I have tried unplugging from computer, from outlet on power strip, different plug ins, turned off in back, front, power strip, I think I have tried everything. I have checked all of my display settings nothing seems to work and even though I dont have hibernation or sleep settings on if I am away too long the monitor will be black when I return and back to square one with turning power on and off for 2 hours to get it going.