Help me stop my FIL getting scammed urgent!

A user is urgently seeking help to prevent their father-in-law from falling victim to a scam by Finex Ltd, an investment firm offering Bitcoin trading. The FIL has already sent €10,000 and is being pressured to deposit another €10,000 to unlock a claimed €100K payout from a locked USDT balance in a Coinbase wallet on the Solana network, which does not support USDT.