Trying to stop the momentum when re spawn - unity3d

Question

I have looked around the web for answers but can't find a working one.
I have tried changing the code and I am pretty sure it's a very easy noob mistake as this is my first game.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class respawn : MonoBehaviour
{
[SerializeField] private Transform player;
[SerializeField] private Transform respawnPoint;
private Rigidbody Rigidbody;
void FixedUpdate()
{
if (player.position == respawnPoint.position);
{
GetComponent<Rigidbody>().velocity = 0;
Rigidbody.angularVelocity = 0;
}
}
private void OnTriggerEnter(Collider other)
{
player.transform.position = respawnPoint.transform.position;
}
}

Answer 1

The very first thing you want to do is to look at the Unity error console. Your code throws multiple errors, they will appear in red. Double-click on an error to be taken to its line in your code.
Also, try get a good editor, like VS Code, as it will help you find issues immediately by adding red wavy underlines. With above two approaches in hand, you will be able to find ~99% of your issues yourself the next time, and then can ask in forums for the remaining 1%.
Let's go through your code step by step:
private Rigidbody Rigidbody;
In Unity you normally want the type in upper case Rigidbody, but the variable name in lowercase rigidbody (even though the C# coding conventions suggest uppercase properties). Either way, don't use the same name as the type, so write:
private Rigidbody rigidbody;
or e.g. (I'm now omitting the default private, though you may also prefer to keep it, and I use a shorter variable name, and clarify its start value):
Rigidbody body = null;
In the following code:
GetComponent<Rigidbody>().velocity = 0;
... you first of all get the rigidbody component again. This isn't needed if you got it once in start (and for repeated usage, can lag), so do it like this:
void Start()
{
rigidbody = GetComponent<Rigidbody>();
}
And secondly, you assign a 0, but you want to assign new Vector3(0f, 0f, 0f), or just
rigidbody.velocity = Vector3.zero;
rigidbody.angularVelocity = Vector3.zero;
Lastly, you write
player.transform.position = respawnPoint.transform.position;
... but player and respawnPoint are already transforms, so you can use the simpler
player.position = respawnPoint.position;
Good luck!

Answer 2

When you enter the Trigger you will be teleported to the respawn position, but you cannot depend on FixedUpdate running on that exact pixel of the respawn position.
The most straigh forward answer is to, well, do the code as you would describe the issue: "When you enter a trigger, set the position to the respawn position and set velocity to 0":
I would change the entire script to:
public class respawn : MonoBehaviour
{
[SerializeField] private Transform player;
[SerializeField] private Transform respawnPoint;
private Rigidbody rigidbody;
void Start()
{
rigidbody = GetComponent<Rigidbody>()
}
private void OnTriggerEnter(Collider other)
{
player.position = respawnPoint.position;
rigidbody.velocity = Vector3.zero;
}
}
and don't forget to populate the player and respawnPoint values in the inspector.
Also, keep in mind that the current code is prone to errors, if you have other objects moving around. Right now, if ANY object enters the Trigger the PLAYER position will be reset. You could fix this with check for player
private void OnTriggerEnter(Collider other)
{
if (other.transform == player)
{
player.position = respawnPoint.position;
rigidbody.velocity = Vector3.zero;
}
}