Bad behavior should be corrected from the ground up.
Start with basic lunging in both directions. Ask for a walk, trot, and canter. The horse will most likely NOT listen to you and be racing in circles like a mad man, spooking, bucking, etc. You MUST be constant and patient in what you are asking. Cluck, tell him 'easy', talk to him until he starts to listen. Work on getting him to slow down, calm down, and respond. Do not work him to long or to hard. A short, calm session is more likely to have an effect than a long, drawn out one.
Be big. When he invades your space or tries to run you over, put on a very angry tone and puff yourself up. Make him KNOW that you are NOT okay with what he is doing. MAKE him back up, walk towards his hindquarters and MAKE him turn away. Invading of ones space is a very, very, dangerous behavior that can get you killed if it is not swiftly corrected.
Bouncing off the walls is yet another behavior I do not tolerate.
Firstly, look at what he's getting. Is it oats or sweet feed? Corn? With some horses, this can really make them go off their rocker. I know from personal experience.
My nine year old was given an oats and sweet feed diet and he became down right uncontrollable. Some horses just to not handle the sugars well, and henceforth should be taken off grain entirely or their energy should be coming strictly from vegetable fats, not straight sugars.
Whats his medical history? Pain caused by sharp points on the teeth, or a painful bean in an uncleaned sheath and greatly add to bad behavior, causing the horse to be distracted and dangerous.
What about tack pain? Does his saddle and bridal fit right? What kind of bit are you using?
What about your experience? Rider confidence and experience pays a HUGE roll in how a horse acts, especially with a higher strung or spooky horse.
Loki is very spooky, and requires a confident rider and handler otherwise he can be dangerous. Sam on the other hand is a very calm and quiet horse, he is a great mount for children as he goes very slow and does not spook at his own shadow. If I was a inexperienced, low confidence rider, Loki could probably kill me if I tried to ride him. Since I quite bluntly, don't put up with his idiocy, I can ride him without to much danger.
He is obviously not ready to be ridden out. Work with him with becoming used to on the ground to 'scary' objects. Work him extensively in a arena or round pen. Set up barrels, poles, or even flour pots and do patterns with him. I find that patterns help a horse relax and become more responsive to the rider. Especially a green or spooky horse.
If possible, ride him in a large pasture. Ride him towards the herd, then stop him, turn him around, and walk him away. Repeat until you are nearly on the herd itself. He needs to learn that no matter what, he is going to have to answer to the person on his back, not the other pretty ponies over the hill. Repeat the go-towards-walk-away until he calmly and gently walks both towards and away from his comfort zone.
I don't suggest riding within the herd itself. There is a pecking order and like with my three boys, flattened ears, bites, and kicks are most likely to be aimed at an intruding horse.
Good luck. And remember, patience is really the key. If nothing else, I'd suggest selling him to an experienced rider and getting an old, been-there-done-that horse. Sam is one of those types, and he's helped me by leaps and bounds gain confidence and better understand horses.
Wait! I'll fix it....