https://coinb.in/#verify brings me to this 7.37 BTC transaction.

So my guess is:
He knew which addresses were yours, then he sent you a raw unsigned transaction. You signed it, broadcasted it, and gave $30k away

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It's too late for you, but as a general warning: you should never execute any code you don't understand on your computer!

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The number of people keeping tens of thousands of dollars in an Electrum hot wallet also surprises me. Those wallets are just waiting to get scammed!

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Following the money, it ended up here, here, and here. Together with other inputs, it's now spread out over many addresses holding exactly 0.256 BTC. The money is probably mixed by ChipMixer, and you'll never find it back

All that's left for you is to provide evidence that Coolserver.host is behind it, but considering he's a Newbie, that account has no value to him anyway.