i have vertical colored lines appearing on the Mini Ipad screen

Try turning the device right off then on again. If this doesn't work, put your device into recovery mode (google putting iphone into recovery mode), its quite easy to do and do a full restore.

Out of everything else, this should fix it.

If it is still happening, you may have to take your device into an apple store and have it looked at.

I had the same problem with my first gen ipad mini. The solution was not to do a hard reset, but instead to push the sleep/off button until the red slider appeared, then slide to OFF. Wait a few seconds then push the sleep/home button until the Apple logo appeared. The lines were gone. I called Apple Support and they wanted $19 to troubleshoot over the phone and $99-$199 to bring to the nearest Apple store. This may not be a permanent fix, but it resolved the issue. I purchased my ipad mini from a local electronics store in May of this year. Believing it to be new and still under warranty I called the AppleCare store and discovered that it had "previously" been purchased in November a year ago and was no longer in warranty. As stated, I've had the device since May and it has worked wonderfully until today when I turned it on and it had colored vertical lines displayed on the screen. The lines would change color at times and even became a solid black stripe. The strange thing was that when taking a screen shot the lines were not noticeable and didn't show up on the picture. The Customer Care support tech told me to search other display issues. On one of the support threads it had something to do with videos/video apps and that is where I saw to do the SLIDER OFF. It worked even when the hard RESET had not.