screen issue

My Lenovo Flex 4 1580 VE had screen issue, so it would work normally with an external monitor except the screen. I ordered a replacement from Amazon and before it arrived, I was playing with current screen to see if it starts. With power on and monitor connected, I tightened the display cable...

I got a Dell Inspiron E1505 off eBay a couple of days ago.The laptop came with the charger and some user guides and installation dvds. It was pre-installed with Windows XP. The computer boots up fine, but the screen shuts off after about 5 seconds. I thought it was a dust problem, so I cleaned...