I had a failed 5000 graft FUE, can I have another FUE surgery?

You can have a second hair transplant if the donor area has a reasonable amount of hair left. Failures are usually the result of technical problems at the time of the surgery. If the first surgery was with FUE, the second surgery should not use FUE or you will have balding in the donor area.  Your available donor area depends upon your original donor density that you had prior to the first hair transplant. Did your doctor measure it?