Hi @The-king, sorry to hear about this.
If the volume keys are defective to the extent that the volume down key is pressed down constantly, I am afraid that there is no way to exit safe mode. This due to the fact that the phone will enter safe mode automatically if the volume down key is pressed down during the boot up.
My suggestion is to get in contact with your local support team in order to have your phone sent to an authorized service center to be examined and possibly repaired. If you have any questions regarding the service such as routines, warranty and consumer laws, these kind of questions are best answered by your local support team as well.
I hope that answered your question!
