Diplays #8 to raise foot and needle and restart but then just displays same thing

Probably the best thing is to take it for service.

You can try searching for a manual:

Make Model manual

incorrect needle
needle not fully up in the retainer
most needles will be just slightly above the foot when it is raised when the needle stroke is at it's upper most point of travel

Perhaps this error list will help you resolve the problem:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwijuKaq-9fJAhUD6WMKHXLVCyYQFggjMAE&url=http%3A%2F%2Fwww.janomeservicevideos.com%2Fwordpress%2Fwp-content%2Fuploads%2F2015%2F02%2FError-Codes.pdf&usg=AFQjCNHyJmEhmZ9Avh-lSL4Y0vVHEYM1yg&cad=rja

Try lowering the pressure foot and the needle and then raise them
again and then restart the machine, and if that doesn't clear the
error message then it's time to service the machine.

My gut instict is to say that you may have a faulty presser foot position sensor. If this goes bad, even if the presser foot is raised, the machine thinks that it is down, no matter what. There are few other issues that could cause this problem, but they are all tied to faulty electronic components. I would earnestly suggest taking your machine in to a Janome dealer or another reputable sewing machine repair shop.

A transcript from the Elna SU manual reads as follows, and the manual can be viewed on line at http://sewingonline.co.uk/instructions/elnasp/

First make a few trial runs with a scrap of material exactly as the buttonhole will be stitched, with the machine adjusted as you intend to use it.
1. Use the embroidery and buttonhole foot. It can be chnged without a screwdriver by using the fixation screw.- With the stitch width knob at "0", turn the selector to zigzag "1".
2. De-center the needle to the left.
3. Set the stitch width knob at 2, with the solid mark on top.
4. Set the stitch length dial between 1/2 and 1/4.
5. a) Mark the desired length on the material.
b) Sew the first side of the buttonhole. Stop with the needle in the material and the mark (right).
c) Raise the foot and pivot the material round the needle. Lower the foot and raise the needle.
6. a) Set the stitch width knob at 4.
b) Sew a few stitches. Raise the needle.
7. a) Set the stitch width knob at 2.
b) Sew the second side and stop just short of the length of the first. Raise the needle.
8. a) Set the stitch width knob at 4.
b) Finish off the buttonhole by sewing a few stitches. Raise the needle.
9. a) Set the stitch width knob at "0".
b) Sew a few stitches to fasten the threads, holding the material back by hand.
10. Open with the buttonhole knife, which you will find in the accessory box.

try lowering the pressure foot and the needle and then raise them
again and then restart the machine, and if that doen't clear the
error message then it's time to service the machine.

Not familiar with your machine, but an important suggestion for all sewing machines:

ALWAYS RAISE the presser foot when threading the top thread. If you did not do this, remove the top thread completely from the machine and start over by RAISING the presser foot and following the thread path. (Do NOT miss any thread guides or thread any out of order!)

Lower the presser foot and thread the needle. (The top thread will pull through the needle ONLY if the presser foot is raised!) RAISE the presser foot and pull at least 5 inches of thread through the needle. Insert your fabric. Lower the presser foot. Hold the thread tail gently in your left hand and with the right hand manually turn the handwheel one rotation. The needle should pull the bobbin thread up through the fabric.

While still holding the top thread tail, "sweep" under the presser foot with a stiletto, scissors, a nail file (anything that will fit under the presser foot) to pull the remaining bobbin thread tail above the fabric. Grab both thread tails and pull them under the presser foot toward the back of the machine. Now, you are ready to take your first stitch.

You can gently hold those thread tails while you slowly power the machine to take the first couple of stitches on your fabric.

Hi. Here's how to attached the zipper foot.

To Attach the Zipper Foot
1. Loosen the large screw at the left of the presser bar and remove presser foot (You do not need to remove the screw).
2. Hook the prongs of the Zipper Foot around the presser bar from the back, and tighten the presser-bar screw.
3. If the raised edge (zipper or cording) is to the right of the needle, adjust the Zipper Foot by loosening the thumb screw at the back of the foot and sliding foot to the left of the needle. If the raised edge is to the left, slide foot to right.
4. With presser foot down, check its position by lowering needle into side notch, making sure it just clears the foot.
5. Tighten thumb screw to lock foot into position.
When raised edge is placed to right -- adjust foot to left of needle.
When raised edge is placed to left -- adjust foot to right of needle.

check youre screen you will see an icon of needle you have got it in the down mode touch it it will raise it next time you sew it will be raised this is an option to have needle in fabric or raised on completion of sewing this is in your manual.
hope this helps mary h

Does the presser foot move at all when the machine is first turned on?
Do the needle and feed teeth calibrate when the machine is first turned on?
You probably need to locate your nearest authorized repair center.