Yes, I know that there will be many problems, but the income of second-hand miners is the same as that of new miners, and the payback period is less. Is there any on the telegram? Can you recommend it to me?
If you are aware then you should be also aware of the warranty.
2nd hand units don't have warranty support so if you receive a defective one you won't be able to get support or a refund.
Anyway, about his telegram go to his website here
https://www.scottofford.com/ and scroll down to find the telegram link. There are used and brand-new miner on his telegram and also try to contact him I believe he can help you look a good 2nd hand miner.