Dumbass UPT post

So I've been at my Amazon for 8 months and I told my brother to come work with me. My schedule is Sunday -wednesday from 9pm-6 30am and his is Tues-friday with the same hours. He picked up overtime shifts for my schedule and the system showed he was scheduled for those days but when he worked those shifts it marked him absent and took UPT from him. HR was no help yesterday and said he wasn't supposed to work that shift even though he got an email saying to show up and it appears on his calendar schedule. He also got paid for the shift. Long story short HR didn't help and he just got fired today. What can I do on my end to help him out? We only have 1 HR at our building I believe (I never met him or her) and yeah.