Same with my acer vx15 i7. I tried connecting it to another screen through hdmi and the display is ok. The technician said it could be the flex cable but I'm not sure for im not an expert with hardware issues, I hope. I can get an answer here regarding with the issue. Thanks

 This flicker issue has to do with a bad connector that Acer seems to want to hide this from customers.. This connector seems to be a common component used in many Acer products.  Over time It will find a way to loosen up and cause this flicker issue . This is why after sending my laptop back to Acer twice without a permanent fix and them wanting me to send it in a third time I decided to look into it myself.  In my case my laptop did not stop flickering completely till I opened the case and fixed it by inserting and attaching a spacer between the top of the display ribbon cable connector where it connects to the motherboard and case bottom so that it has no room to work itself out.  After doing this I never had the flicker problem again. 

The spacer needs to be a material soft enough to constantly apply pressure to the back of the connector while not touching anything else. I cut a small piece of thin foam padding to the size of the connector and taped it to the back of the case with electrical tape. When I screwed the back of the laptop case in it just applied pressure to the back of the connector.  Since then I have had no more flicker issues.