Why won't the screen stay down?
The digitizer seems to be poping out of the body near the bottom. This started happening after the replacement. Is there a certain way to fold the flex cable?
Announced October 22nd and released November 12th, 2013. The iPad mini 2, also known as the iPad mini with Retina Display, has all the pixels of the iPad Air in a smaller 7.9" form factor.
This does sound like the ribbon may be pushing up on the digitizer. It happens when the digitizer flex ribbon is bent in the wrong direction when the digitizer is installed. It's really common when replacing ipad screens, and the minis are especially a pain. It will cause a lifting pressure on the screen. When properly installed, the digitizer should lay flat without needing to force the bottom to stay shut. The Digitizer Ribbon will effectively make a sort of sideways W shape. Sometimes the adhesive on a cheap digitizer is pretty bad, but the digitizer should still rest flat without having to be held in place.
To ensure the cable routes correctly:
1. Plug the digitizer flex ribbon in
2. Prop the digitizer up at a 90 degree angle so that the bottom edge of the digitizer rests on the bottom edge of the iPad. The two will make an L shape, where the digitizer is verticle, and the iPad is horizontal. (I use my 'helping hands' to keep it in place.)
3. Plug in the LCD flex ribbon, and screw it in.
4. Install the metal LCD Back Plate, making sure to keep your flex ribbons tucked under it as much as possible.
5. Screw in the LCD, still making sure to keep your Digitizer Flex Ribbon tucked under it as much as possible.
6. Slowly fold the digitizer down into place. I find "sliding" the Digitizer from side to side about 1/4" as you lower it can help the Digitizer Flex Ribbon slide under the LCD.
7. If the Digitizer still doesn't want to lay flat without assistance, try using a plastic tool to gently push it towards the LCD while lowering the Digitizer. This will help it bow in the right direction. It will make a sort of sideways W shape. This combined with the slight sliding mentioned earlier should guide it into position.
Be sure the Digtizer Flex Ribbon doesn't get stuck in the adhesive and crease under the Digitizer as you lower it. Also, as iMedic stated, the old glue must be completely removed before new glue can stick to the chassis. It must also be prepped with alcohol or something like it.
Don't forget to tape off the metal parts of the lower section of the Digitizer, and also the Home Button Ribbon. This can help prevent erratic behavior.
Alternatively, if the corner of the aluminum chassis has been bent in from a drop, then the Digitizer will not be able to lay flat in that corner. This will cause the Digitizer to bow up in that corner and always want to lift up. If this is the case then pressing the Digitizer down in that corner can crack the Digitizer. The corner of the aluminum chassis will have to be re-formed to make room for the Digitizer. This can be done many ways. There is a tool to bend the corners back, but it is expensive. I have had success a few ways, as unorthodox as they may seem.
In the toolkit supplied with the Digitizer is usually a long, metal spudger. It has a flat head and a rounded end on the handle. That rounded edge on the handle is close to the same curve as the aluminum chassis. If you use the metal spudger as a chisel with a hammer, you can use the rounded edge on the handle to tap the corner of the chassis back into shape. I had someone hold the iPad upright on a hard surface while I worked on the corner. Be careful, as the aluminum is soft. Massage the corner a little at a time until the digitizer will sit flat in place. Also, don't hit your iPad with the hammer.
Another option is to use a micro-die grinder or Dremel tool. The sanding drums are also a very similar curve, and make the repair very quick and easy. Hold the dremel at a 90 degree angle to the iPad so you don't round the edge of the chassis off. Remove a little at a time until the Digitizer fits in place.
All in all, it takes a bit of fiddling with it to get it to go into place. Keep trying and you'll get it to lay perfect. I hope this helps a bit. Happy Repairs!