Need help with balancing a homebrew subclass

I’m new here. So I will be running a campaign and one of my players gave me a homebrew monk subclass they would like to play. I don’t have a lot of experience with balancing, so I’d like to hear some of your views.

Here is the subclass in question.

3rd level ability Go Beyond!

You channel your inner energy and put what you can without going over your limit into one strike. Make only one attack this turn, and if it hits roll normal damage and 2d8. Add this in as force damage.

As a bonus action you can go past your limit and increase your own power after expending two ki points. Outputting damage at the cost of your own health. Roll 2d6 and add that to your attack’s damage. You take half of the damage you output with this roll, your body simply can not safely handle this amount of energy. (scales up to 4d6 at 6th level, 6d6 at 11th, 8d6 at 17th.)

3rd level ability Endurance! Speak some encouraging words to yourself, and become boosted from your own form of personal inspiration. Spend a ki point and as a bonus action roll a martial arts die and add your wisdom modifier to it. You gain this number in temporary hit points. You can only use this ability up to three times before needing to take a long rest.

When you gain this ability, once per short rest if you go down in a combat due to extra damage that you inflicted yourself by pushing past your own limits, you do not go down. You instead end your turn at 1hp.

6th level ability Smash! (power increases at 11th level) Something comes over you and you push yourself past your limit to destroy an enemy. You’re able to channel your power into one powerful attack.

Once per turn as an action you can force one creature in front of you to make a Dexterity saving throw after you hit them with an attack DC = 8 + Proficiency + Dexterity Modifier. On a fail they take 6d6 Force damage and they are shot back 20 feet.

If they succeed the saving throw they take half damage and are not pushed back. You may do this a number of times equal to your Constitution modifier before needing to take a long rest.

Using this ability more than once between long rests is possible. But after the first use the user begins to take damage from exerting such a powerful blast. If used more than once between a long rest, the user receives half of the damage dealt. You spend 3 ki points using this ability.

11th level ability This is it! As a last effort to defeat your enemy you feel a surge of kinetic energy through your body. While you are below 1/2 your total hit points, you gain the following for 1 minute: • Your unarmed attacks deal additional damage equal to your proficiency bonus, but you take an equal amount of damage. • Inspiration. As a bonus action, Inspire your allies to fight and give their all! Your allies gain temporary hp equal to your level. One use •Limit Break. you have advantage on Strength and Constitution saving throws.

11th level ability Smash! (improved smash) You have become more powerful overtime, and are always trying to learn how to control your power better. Once per turn, as an action you can attack one target or target up to 3 creatures in a 20 foot cone to make a Dexterity saving throw DC = 8 + Proficiency + Dexterity Modifier.

Those who fail take 6d8 Thunder damage and are shot back 20 feet If they succeed the saving throw they take half damage and aren’t knocked back

You may do this a number of times equal to your Constitution modifier before needing to take a long rest.

Using this ability more than once between long rests is possible. But after the first use the user begins to take damage from exerting such a powerful blast. The user receives half of the damage dealt. You spend 3 ki points using this ability. Add another ki for each other person hit, max of 2 more so 5 ki points.

17th level ability Final Smash! At 17th level, you’re able to unleash the most devastating attack in your arsenal. You cause a burst of energy originating from your fist, every creature within a 30 foot radius must make a strength saving throw or take 8d10 Force damage. Creatures within 30 feet are knocked prone, this can also be used directly on a creature which forces them to be knocked back 30 feet and they are stunned if they fail the save. Creatures who succeed the saving throw take half damage and suffer no other effects. Using this on the ground causes 15 foot radius to become difficult terrain. This deals double damage against objects. You can use this a number of times equal to half your Con mod, and gain a point of exhaustion each time you use it. After using it one time between a long rest, you take half the damage you deal back. You regain all uses at the end of a long rest.